Melanoma Flashcards
A 70-year-old man is referred for evaluation of a 2.2 x 1.3-cm pigmented lesion on the right side of the neck over the midsection of the sternocleidomastoid muscle. Punch biopsy shows lentigo maligna melanoma with a Breslow thickness of 0.6 mm. Wide surgical excision with a 1-cm margin is performed. A photograph is shown above. The specimen report upgrades the Breslow thickness to 1.2 mm. Further evaluation, including CT scan of the head, neck, chest, and abdomen, shows no associated metastases. Which of the following represents the amount of additional margin of excision that is needed for adequate local management of this lesion?
(A) No additional margin is necessary
(B) 0.5 cm
(C) 2 cm
(D) 3 cm
(E) 5 cm
The correct response is Option A.
Breslow thickness measured from the top of the granular layer to the deepest level of tumor is the single most important factor in the prognosis of melanoma. Sampling error failing to reveal the deepest point of a lesion during incisional biopsy techniques is quite common, even in experienced hands. This leads to possible need for reexcision and sometimes lymph node management. The punch biopsy either picked up a thinner area or did not include the full thickness of skin. Because of the surface extent of the lesion, a punch biopsy is still appropriate as the initial diagnostic method; however, when the entire lesion is analyzed, the thicker areas may be revealed and call into question the adequacy of the original margin of excision. In this case, no additional margin is necessary. A study performed by the World Health Organization has shown that for melanomas less than 2 mm, a surgical margin of 1 cm is just as effective as a 3-cm margin, and there is no difference in locoregional recurrence, in-transit metastases, or five-year survival rates.
Current practice recommendations advise a margin of excision of 0.5 to 1 cm for in situ melanoma. Invasive lesions with a Breslow thickness between 0 and 1 mm should have a 1-cm margin of excision. For lesions between 1 and 2 mm, a 1- to 2-cm margin is acceptable, using closer to 2 cm when the anatomic area is more forgiving, such as the trunk, or when the thickness is closer to 2 mm. Lesions between 2.1 and 4 mm should have a 2-cm margin. For lesions thicker than 4 mm, a margin of at least 2 cm should be used, but a 3-cm margin should be considered if ulceration of the tumor is present.
Which of the following skin lesions meets criteria for sentinel lymph node biopsy (SLNBx)?
(A) Basal cell carcinoma (8 cm wide) on the anterior chest
(B) Melanoma (1.6 mm thick) of the breast with bulky axillary adenopathy
(C) Melanoma €‘in €‘situ on the shoulder
(D) Squamous cell carcinoma (1.8 cm wide) on the dorsum of the hand
(E) Squamous cell carcinoma (2 cm wide) in a 26 €‘year €‘old burn scar of the foot
The correct response is Option E.
Sentinel lymph node biopsy (SLNBx) is a well €‘established staging procedure for melanoma and breast cancer. A patient with melanoma in situ, by definition, does not have invasion and, therefore, would not benefit from SLNBx. Conversely, the patient with bulky adenopathy most likely has regional metastatic disease and requires formal lymphadenectomy. Indications for SLNBx in non €‘melanoma skin cancers are evolving and currently include squamous cell carcinoma greater than 2 cm in diameter, Merkel cell carcinoma, and Marjolin ulcer (burn scar carcinoma). Basal cell carcinomas almost never demonstrate lymphatic spread; therefore, SLNBx would not add any diagnostic information.
A 73 year old man is referred to the office by his primary care physician for evaluation of discoloration of the nail of the left thumb (shown), which has been present for the past seven years. The patient says the appearance of the nail has not changed recently. Biopsy of the nail matrix shows malignant melanoma of indeterminate depth. Which of the following surgical procedures is the most appropriate management?
(A) Elective lymph node dissection and amputation at the metacarpophalangeal joint
(B) Elective lymph node dissection and nail ablation
(C) Sentinel node biopsy and amputation at the level of the interphalangeal joint
(D) Sentinel node biopsy and excision of skin with 1-cm margins
(E) Sentinel node biopsy and ray amputation of the carpometacarpal joint
The correct response is Option C.
The annual incidence of melanoma has increased significantly from a lifetime risk of 1:1500 in 1900 to the current risk of 1:35. Nail apparatus melanomas, and specifically subungual melanomas, pose a difficult problem because they are often diagnosed late. Late diagnosis correlates with thicker melanomas and greater risk of metastasis. Approximately 20% to 25% of subungual melanomas may be amelanotic. Sentinel node biopsy has become the standard of care, and since its advent, elective lymph node dissection is no longer recommended.
Because of the proximity of the nail matrix to the periosteum and bone, adequate resection margins are not achieved with standard wide excision of 1 to 2 cm, and recommendation for excision is at the distal interphalangeal joint of the finger or interphalangeal joint of the thumb. Melanoma can track along the neurovascular bundles. Amputation at a more proximal level is not needed and does not improve prognosis. More proximal amputation also results in a critical loss of function, particularly concerning the thumb.
The presence of pigment in the paronychial area (Hutchinson sign) is shown in the photograph. An area of pigmentation in the eponychium is almost pathognomonic for subungual malignant melanoma.
A 67-year-old woman presents with a 7-mm, irregular, asymmetrical, heterogeneous brown macule that has been enlarging for the past 2 months. An excisional biopsy with 2-mm margins shows melanoma. After tumor thickness, which of the following pathologic features is most indicative of her prognosis?
A) Clark level
B) Macule diameter
C) Mitotic rate
D) Morpheaform features
E) Ulceration
The correct response is Option E.
This lesion has all of the clinical features suggestive of melanoma: asymmery, irregular border, heterogeneous color, diameter greater than 6 mm, and evolution. After thickness, ulceration is the most important prognostic indicator for melanoma, and has become an important component of T staging. The prior AJCC staging system did consider mitotic rate but recent evidence has shown that ulceration is a more important prognostic indicator. Mitotic rate is no longer a factor in determining T stage, whereas ulceration is. Clark level and lesion diameter are not independent predictors of outcome for melanoma. Morpheaform features are associated with poorer outcomes in basal cell carcinoma.
A 42-year-old man has Clark Level III melanoma with a Breslow thickness of
1.5 mm in the concha of the right ear. Physical examination shows no other palpable masses. In addition to wide excision of the lesion, which of the following is the most appropriate step in management?
A ) Infraclavicular lymph node dissection
B ) Posterior neck dissection
C ) Sentinel lymph node biopsy
D ) Superficial parotidectomy
E ) Total parotidectomy with radical neck dissection
The correct response is Option C.
The lymphatic drainage of the external ear is generally believed to follow its embryologic development. In general, the external auditory canal and the superior portions of the ear drain into the mastoid region and the superior cervical chain of lymph nodes. The concha and meatus are traditionally considered to drain into the parotid and/or the infraclavicular lymph nodes. However, recent studies with lymphoscintigraphy and sentinel lymph node mapping have demonstrated that lymphatic drainage can be unpredictable.
Sentinel lymph node biopsy, which also serves to stage the extent of disease, is the most appropriate management after wide excision of the lesion. It is the most specific means of identifying regional lymph node spread. The sentinel node may be located in the parotid gland, the infraclavicular node, or some other part of the cervical chain of lymph nodes.
An 88-year-old woman comes to the office because of the 2-cm pigmented lesion on the vertex of the scalp shown. There is no evidence of cervical or suboccipital lymphadenopathy. Examination of a specimen obtained on punch biopsy shows a Breslow thickness of 2.1 mm, Clark Level IV, two mitotic figures per high-power field, and no evidence of ulceration. Which of the following is the most appropriate management?
A) Excision with 1-cm margins and bilateral cervical lymphadenectomy
B) Excision with 2-cm margins and delayed sentinel lymph node biopsy
C) Excision with 3-cm margins and bilateral cervical lymphadenectomy
D) Preoperative lymphoscintigraphy, excision with 1-cm margins, and immediate sentinel lymph node biopsy
E) Preoperative lymphoscintigraphy, excision with 2-cm margins, and immediate sentinel lymph node biopsy
The correct response is Option E.
In the patient described with an intermediate thickness tumor (1–4 mm) and clinically negative neck, the most appropriate treatment is wide excision with 2-cm margins (shown) and a concurrent sentinel lymph node biopsy. The defect may be reconstructed with a local flap or skin graft depending on patient and surgeon preference. In Stage I and II melanomas (localized disease T1-4, and no evidence of regional lymphadenopathy, N0), Breslow tumor thickness is the most important predictor of local recurrence, regional/distant metastases, and overall survival.
Current recommended excisional margins are 0.5 to 1.0 cm for melanoma in situ/lentigo maligna. For invasive lesions less than 1 mm thick, a 1-cm margin is adequate. Lesions with Breslow thickness of 1 to 2 mm should be resected with a 1- to 2-cm margin, using closer to 2 cm when the anatomical area is more forgiving (scalp/trunk), the thickness approaches 2 mm, or the lesion displays more aggressive histopathologic features, such as ulceration, lymphovascular invasion, tumor regression, or a mitotic index greater than one figure per high-power field. Lesions between 2 to 4 mm are adequately treated with 2-cm margins. Balch, et al., have shown that 2-cm margins are safe for lesions of intermediate thickness with equivalent survival rates, less use of skin grafting, shorter hospital stays, and lower medical costs when compared with more aggressive peripheral margins. When possible, 3-cm margins should be used for tumors greater than 4 mm thick because of their high local recurrence rate (greater than 20%).
Patients with intermediate-thickness melanomas have a 20 to 25% chance of microscopic regional disease. Before the advent of sentinel lymph node biopsy, elective lymphadenectomy (ELD) was advocated for patients with intermediate-thickness melanoma because of a significant improvement in overall survival at 10 years. The primary disadvantage of routine ELD, however, was that approximately 75 to 80% of patients underwent an unnecessary procedure.
The status of the sentinel lymph node is a powerful predictor of survival in melanoma because it identifies (1) those patients with a relatively favorable prognosis requiring no further therapy; and (2) high-risk patients who might benefit from additional surgery (completion lymphadenectomy) and interferon. Current indications for sentinel lymph node biopsy include all of the following: male patients with truncal melanoma less than 0.76 mm thick (9% incidence of nodal metastasis); all patients with melanoma thickness 0.76 to 1.0 mm (5% incidence of nodal metastasis); male patients with “thin” melanomas with aggressive features (Clark Level III or greater, ulcerated, evidence of regression, or axial location; these patients have a 10% risk of metastasis); and all melanomas greater than 1 mm in thickness.
In the scenario described, 1-cm margins would be too narrow. A 3-cm margin is excessive for the lesion described. As noted, elective lymphadenectomy has been replaced with sentinel lymph node biopsy in a clinically negative neck. Finally, sentinel lymph node biopsy should be performed at the time of the primary tumor resection if possible due to variations in the lymphatic drainage that may occur after wide excision, skin grafting, or flap closure.
A 60 year old man is diagnosed with melanoma of the forehead. In addition to wide local excision, in which of the following tumor stages is sentinel lymph node biopsy indicated?
(A) Tis N0 M0
(B) T2a N1 M0
(C) T2b N0 M0
(D) T3b N1 M0
(E) T4a N0 M1
The correct response is Option C.
Sentinel lymph node biopsy (SLNB) is the standard of care for intermediate-thickness melanoma of the trunk and extremities and is recommended when possible for intermediate melanoma of the head and neck, such as those staged T1b N0 M0. SLNB is more complicated in the head and neck because of greater variation in the lymphatic drainage systems in those areas and because of the close proximity of the primary tumor to first €‘echelon lymph nodes. However, prospective studies have reported no false negatives, and SLNB results are of great prognostic value and may be used to guide adjuvant systemic protocols. Positive sentinel lymph nodes are identified in 15% to 21% of patients, and then complete nodal dissection yields additional positive nodes in up to 20% of patients. The effect of elective lymph node dissection on patient survival rates has not been determined. Nor has local or regional control in the clinically negative neck among patients with stage I and II melanoma.
SLNB is indicated in intermediate melanoma with lymph nodes that are clinically negative. Intermediate melanoma in the head and neck includes stages IB and II. In these stages, tumor characteristics include T1b (Breslow thickness of less than 1 mm with ulceration, or Clark level of IV or V), T2 (Breslow thickness of 1.01 to 2 mm), and T3 (Breslow thickness of 2.01 to 4 mm).
A T1a tumor is a thin, less aggressive melanoma with a Breslow thickness of less than 1 mm without ulceration or a Clark level below III. Because it is not yet intermediate, this tumor is not appropriate for SLNB. A patient with an N1 tumor has a clinically positive neck, which prohibits SLNB. A T4 tumor is a deep melanoma, with a Breslow thickness of more than 4 mm. Because it is no longer intermediate, it is not appropriate for SLNB.
A 40-year-old, right-hand-dominant man comes to the office because of a 2-mm pigmented lesion beneath the thumbnail of the left hand. He says that he first noticed the lesion within the last week. The patient recalls no trauma to the thumb. He has no other fingernails or toenails with similar streaking. Biopsy of a subungual lesion is most appropriate after which of the following periods of time has passed without change?
A) 0 to 3 Weeks
B) 4 to 6 Weeks
C) 7 to 9 Weeks
D) 10 to 12 Weeks
E) 13 to 15 Weeks
The correct response is Option B.
The prognosis for a subungual melanoma is worse than that of cutaneous melanoma. Often, there is a delay in the diagnosis of subungual melanomas; in practice, it is better to be highly suspicious of any pigmented lesion beneath the nail and perform a biopsy. According to recent research, the 5-year survival rate for a patient with a subungual melanoma ranges from 28 to 30%. The 10-year survival rate drops to 0 to 13%. Clearly, this is a devastating disease, and over-vigilance regarding diagnosis is recommended. The current recommendation is to perform a biopsy of any subungual lesion after 4 to 6 weeks without significant change.
A 67-year-old man with a large lentigo maligna on the left cheek comes to the office for closure after undergoing excision. Which of the following steps is most appropriate for the surgeon prior to performing a cervical-facial rotation flap?
A) Await permanent pathology results
B) Confirm negative margins by Mohs micrographic surgery
C) Evaluate the margins clinically with a Wood lamp
D) Perform confocal microscopy
E) Refer the patient for sentinel node biopsy
The correct response is Option A.
Lentigo maligna is a slow-growing lesion with a substantial radial growth pattern before progressing to invasion in most cases. These lesions often occur in the head and neck region of older patients with a history of sun exposure. Clinical occurrence is variable, but many appear as irregular, sometimes extensive, pigmented patches on the face. Staging of these lesions follows the American Joint Committee on Cancer guidelines, and prognosis is based on depth of invasion. Need for sentinel node biopsy is based on staging and is independent of resection size.
Wide local excision of the lesion is the current standard of care, but the surgical margin for successful excision remains controversial. Alternative techniques have been investigated to improve the 8 to 20% recurrence rates associated with standard excision with 5-mm margins. Mohs micrographic surgery shows promise in the treatment of this disease, but there remains difficulty in interpretation of melanocyte proliferation on frozen section, leading to the proposal of modifications of the procedure, including sending the final Mohs margins for rush permanent section evaluation for verification of clear margins, the so-called “slow Mohs.”
Clinical evaluation of margins with Wood lamp may be useful in evaluating the clinical extent of the lesion but is not adequate for determination of surgical margins. Confocal microscopy is a new technique that allows examination of melanocytes without biopsy. This modality may be useful in diagnosis of lentigo maligna, but availability is currently limited and requires training in interpretation of images.
Hutchinson’s freckle is another name for which of the following types of melanoma?
(A) Acral-lentiginous
(B) Lentigo maligna
(C) Mucosal
(D) Nodular
(E) Superficial spreading
The correct response is Option B.
Hutchinson’s freckle is a misleading term for lentigo maligna melanoma, a melanoma in situ that is found within the layers of the epidermis only. This lesion typically occurs in fair-skinned, elderly persons and manifests as a macule or patch of darkened skin on the face or other sun-exposed areas. Although 5% to 10% of all melanomas can be classified as lentigo maligna, the risk for development of invasive melanoma in affected patients has been shown to range from 5% to 30% in various studies. Slow growth, often for a period of 10 to 20 years, is common initially and is then followed by an aggressive, invasive phase.
Which of the following percentages best represents the risk of transformation of a congenital giant nevus to malignant melanoma?
(A) 10%
(B) 20%
(C) 30%
(D) 40%
(E) 50%
The correct response is Option A.
Although it is generally accepted that giant congenital nevi may undergo transformation to malignant melanoma, the exact incidence is difficult to determine, due in part to limitations in methodology of the available studies. Recent reports cite an incidence ranging from 2.9% to 12.2%.
Giant congenital nevi at greatest risk for transformation to melanoma are those lesions that have a predicted largest diameter of 20 cm in adulthood. Current recommendations regarding the timing of excision are controversial, but these lesions should be removed as early as possible in childhood.
In addition to congenital melanocytic nevi, other precursor lesions that can degenerate into malignant melanoma include common acquired melanocytic nevi, dysplastic nevi, and melanoma in situ.
An 18-month-old boy has a 25-cm pigmented lesion on his back. Which of the following is the most appropriate management?
(A) Observation with photographic mapping
(B) Intralesional injection of interferon gamma
(C) Dermabrasion
(D) Tunable dye laser ablation
(E) Excision
The correct response is Option E.
This 18-month-old boy has a giant congenital nevus on the back. Congenital nevi can be classified as “giant” according to several criteria, including those lesions that are larger than 20 cm in diameter, lesions that are greater than twice the size of the patient’s palm, and those nevi for which excision and primary closure cannot be performed as a single procedure. Because of the potential for malignant transformation, surgical excision of the entire lesion is recommended. Although the actual risk for melanoma is controversial, one study reported that approximately 8% of patients with giant congenital nevi developed melanoma during the first 15 years after the initial appearance of the nevus.
Although observation with serial photographic mapping is advocated in patients with familial dysplastic nevus syndrome, it is not appropriate in a patient with a giant congenital nevus because of the association with malignancy. Intralesional injection of interferon gamma is indicated for patients who have confirmed malignant melanoma. Dermabrasion and laser ablation will not remove all of the immature melanocytes within the lesion. In addition, the resultant hypopigmentation seen following treatment may hinder any future monitoring for signs of malignant degeneration.
A 62-year-old man has a lesion of the left pinna. Examination of a specimen obtained on biopsy shows a 2.01-mm-thick melanoma with no ulceration, 11 mitoses, and a positive deep margin. The surgeon’s decision to perform sentinel node biopsy is most heavily influenced by which of the following factors?
A) Breslow thickness
B) Head and neck location
C) Lack of ulceration
D) Number of mitoses
E) Positive deep margin
The correct response is Option A.
Head and neck melanomas in general were thought to be distinct from other anatomic sites. Clearly there can be reconstructive and functional issues that are unique, such as in an ear melanoma. In general the first Multicenter Selective Lymphadenectomy Trial (MSLT-1) concluded that for intermediate-thickness melanoma (1-4 mm), the status of the sentinel node was the most powerful predictor of outcome. In an interim report in 2006, well before the final report in 2014, the specifics on what percentage of patients had melanoma of the head and neck in the MSLT-1 trial were not described, but what was reported was a lower rate of identification of a sentinel node in the neck versus lesions that mapped to the groin or axilla. This led many to conclude that the utility of the sentinel node biopsy in the head and neck was in question. More recent data from multiple high-volume institutions have concluded that identification of the sentinel node for head and neck melanoma is as accurate as other sites in the body, including similar false-negative rates and impact on prognostication.
Mitotic rate does not affect staging above 1-mm thick lesions, and although ulceration can, it does not influence the rationale to perform a sentinel node biopsy in intermediate thickness tumors. In thinner melanomas, a positive deep margin may be an indication for a sentinel node biopsy, but not for a tumor greater than 1-mm thick. The fact that lymphoscintigraphy may map the sentinel node to the parotid region means that the surgeon should be prepared to do a parotidectomy with facial nerve preservation, although recently less-invasive techniques have been described.
A 68-year-old man has the lesion shown in the photographs above. (None supplied) A satellite lesion is noted 2 cm from the primary lesion. Findings on laboratory studies and radiographs of the chest are normal. Histologic examination of a biopsy specimen of the primary tumor shows findings consistent with Clark’s level IV melanoma. The tumor has a Breslow’s thickness of 2.8 mm. There is no palpable adenopathy or distant metastases.
According to the American Joint Committee on Cancer, which of the following is the correct clinical classification stage of this tumor?
(A) Stage 0
(B) Stage I
(C) Stage II
(D) Stage III
(E) Stage IV
The correct response is Option D.
The staging of melanomas involves three descriptors: T, N, and M. The T descriptor is based on the diameter or surface area of the tumor. The N descriptor describes nodal status. The M descriptor indicates distance of metastasis beyond the neck. This staging criteria allows physicians to predict patient outcomes and choose appropriate therapy based on comparisons with patients in large studies.
This patient’s tumor is classified as T4 N0 M0, or Stage III. Although earlier staging classifications placed patients with T4 tumors into a stage IIB subgroup, this has recently been changed by the American Joint Committee on Cancer because of the more aggressive behavior of melanoma and the similarity of disease outcome to other Stage III tumors.
Breslow’s thickness typically takes precedence over Clark’s level in the classification of melanoma; however, because this patient has a satellite lesion, which represents a more advanced level of disease, the tumor is classified as T4. Satellite lesions, defined as those lesions located within 2 cm of the primary tumor, affect tumor classification. In contrast, secondary lesions farther than 2 cm from the primary tumor are considered in-transit metastases, which influence nodal classification. The patient has not been shown to have palpable nodes or distant organ metastases; therefore, the tumor is classified as N0 and M0 respectively.
A newborn is evaluated for a congenital melanocytic nevus encompassing the right temporal and parietal scalp and the right hemiface, sparing the nose and lips. There is no family history of melanoma. The parents are interested in discussing treatment options for this condition and ask about the risk of malignant transformation. Which of the following is the approximate risk of melanoma in this patient?
A) 2%
B) 10%
C) 15%
D) 20%
The correct response is Option A.
Multiple studies have shown that surgical treatment of giant congenital melanocytic nevi does not reduce the risk of melanoma. Overall, the risk of melanoma in this population ranges from 0.7 to 2.9% compared with the 0.6% melanoma risk in the general population. The total number of cases of giant congenital melanocytic nevi is small, as this is a rare condition, and most of these cases do not go on to develop melanoma. Rather, melanoma appears to be generic biologic risk rather than related to the nevus itself. The risk of melanoma is highest in trunk lesions rather than other areas of the body. Furthermore, melanoma does not always occur in the giant congenital nevus itself, but may arise from a satellite lesion instead.
A 70-year-old man has a T3 N0 M0 melanoma involving the skin of the preparotid region. In addition to wide local excision and superficial parotidectomy, which of the following is the most appropriate next step in the management of the regional lymph nodes?
(A) Observation
(B) Prophylactic radiation therapy
(C) Sentinel node biopsy
(D) Modified radical neck dissection
(E) Radical neck dissection
The correct response is Option C.
This patient has a T3 melanoma, which is defined as a tumor that has a Breslow’s thickness between 1.5 and 4 mm, or is designated as Clark’s level IV. Because this melanoma is of intermediate thickness and there are no palpable regional lymph nodes, it is classified as Stage II. In addition to local excision and superficial parotidectomy, sentinel node biopsy is currently recommended to rule out the presence of micrometastases in patients with these lesions.
Lymphatic invasion has the greatest influence on prognosis, but the amount of tumor burden within the lymphatic system also affects prognosis. Approximately 30% to 40% of patients with melanomas of intermediate thickness and no palpable lymph nodes in the neck have subclinical nodal micrometastases; lymph node dissection results in increased survival in this subgroup. However, performing elective lymph node dissection in all of these patients, without identifying those who would benefit most, would subject the remaining 60% to 70% who do not have demonstrable micrometastases to unnecessary morbidity without increasing survival advantage. Sentinel lymphadenectomy using vital blue dye and radiocolloid for mapping can be performed to identify the subgroup in which regional lymphadenectomy should be performed.
Clinical observation followed by neck dissection when regional lymph nodes become apparent is not an acceptable option.
Although prophylactic radiation therapy has been shown to produce benefits similar to elective lymph node dissection in patients with tumors of intermediate thickness, it subjects approximately 66% of patients to unnecessary morbidity. As other means of identifying micrometastases become available, radiation therapy should be considered as a valid treatment alternative in selected patients.
Neck dissection is indicated for patients with stage II tumors who have micrometastases identified via sentinel lymphadenectomy and in patients who have stage III melanoma. The dissection should include levels I through V as well as any other nodal groups that may be at risk. Neck dissection has more of a staging role when it is performed in a patient with a Stage II tumor who has not undergone sentinel lymphadenectomy. A modified dissection, which spares the sternocleidomastoid muscle, internal jugular vein, and spinal accessory nerve, is often preferred. Radical neck dissection is typically performed only if these structures are involved with tumor or the surgeon is inexperienced and/or unfamiliar with the modified approach.
A 75-year-old woman who has a discolored 4-mm lesion of the nail bed of the nondominant left thumb after undergoing removal of the nail plate for management of chronic paronychia. A biopsy specimen of the lesion shows subungual melanoma with a thickness of 3 mm. The above MRI (No images) shows possible tumor tracking along the ulnar neurovascular bundle. Lymphoscintigraphy shows two positive nodes in the axilla.
Which of the following is the most appropriate level of amputation?
(A) Carpometacarpal joint
(B) Metacarpal diaphysis
(C) Metacarpophalangeal joint
(D) Proximal phalanx diaphysis
(E) Interphalangeal joint
The correct response is Option D.
This patient has a subungual melanoma, an uncommon, aggressive tumor most often seen in the thumb. Excisional biopsy should be performed immediately to distinguish this type of tumor from squamous cell carcinoma, basal cell carcinoma, pyogenic granuloma, glomus tumor, or giant cell tumor. Amelanotic tumors, which are often diagnosed late, comprise approximately 30% of all subungual melanomas. A Clark’s level cannot be determined in patients with subungual melanoma because of the absence of subcutaneous tissue within the nail matrix. Although in situ melanomas are associated with a relatively good prognosis, all other forms of subungual melanoma are associated with poor prognoses. The outcome is particularly poor in patients with ulcerated lesions.
Patients with melanoma must be evaluated for the presence of local, regional, and distant metastases. Consultation with a medical oncologist is needed; MRI is helpful in determining the extent of local disease. However, the MRI findings may be confused with inflammatory changes. Melanomas can extend along the neurovascular bundles.
In patients with localized subungual melanomas, amputation just proximal to the most distal joint is recommended to clear disease while maintaining length and function of the digit. Sentinel node biopsy will determine tumor staging and the need for lymphadenectomy. In order to maintain thumb function following amputation, Z-plasty, detachment of the first dorsal interosseous tendon, and a more proximal reattachment of the adductor pollicis tendon can be performed to deepen the first web space and effectively lengthen the thumb.
More distal amputation will not clear local disease and will instead increase the risk for local recurrence. A more proximal amputation will not improve the poor prognosis and will also result in a significantly less functional digit, especially when the thumb is involved.
A 60-year-old man comes to the office because of a 2-cm pigmented lesion on the right lower back (shown) that has enlarged progressively for 3 years. No lymph nodes are palpable. Examination of a specimen obtained on punch biopsy shows a Clark Level IV malignant melanoma with a Breslow thickness of 1.2 mm and ulceration. Which of the following is the most appropriate management?
A) Excision with 2-cm margins
B) Preoperative lymphoscintigraphy, sentinel lymph node biopsy, and excision with 1-cm margins
C) Preoperative lymphoscintigraphy, sentinel lymph node biopsy, and excision with 2-cm margins
D) Excision with 1-cm margins, followed by lymphoscintigraphy and sentinel lymph node biopsy at a later date
E) Excision with 3-cm margins, split-thickness skin grafting, and right axillary lymph node dissection
The correct response is Option C.
A melanoma 1.2 mm in thickness on the lower back would best be excised with 2-cm margins and a concurrent sentinel lymph node biopsy. Although a few studies cite the adequacy of a 1-cm margin for tumors less than 2 mm in thickness, a punch biopsy was performed in the scenario described, and the final pathology of the complete lesion could show a thicker lesion. In a location where there is sufficient tissue, a 2-cm margin is more appropriate for a lesion that is over 1 mm in thickness. Most authors cite resection margins of 5 mm for melanoma in situ, 1 cm for melanoma less than 0.8 mm, and 2 cm for melanoma between 0.8 and 4 mm.
Patients with intermediate thickness lesions of 0.8 mm to 4 mm have a 20 to 25% incidence of microscopic regional disease. Sentinel lymphadenectomy serves to identify patients at high risk who may be candidates for adjuvant treatment. At this time, sentinel lymph node biopsy is a diagnostic, but not yet proven, therapeutic procedure.
In patients with melanomas greater than or equal to 1 mm in thickness and no clinical evidence of regional lymph node metastases, lymphoscintigraphy is performed preoperatively to define the lymphatic drainage and demonstrate sentinel lymph node location. Sentinel lymphadenectomy is performed most accurately at the time of wide and deep excision of the primary lesion. Later, sentinel lymph node localization may be impaired if the primary lesion has been excised deeply, as the drainage patterns may have been altered by the previous procedure.
It is imperative to obtain preoperative lymphoscintigraphy in areas with a high likelihood of aberrant drainage patterns. In the trunk, unpredictable drainage patterns can occur in 20 to 35% of cases.
Which of the following additional findings in the patient shown is indicative of the most life-threatening syndrome?
A ) Hydrocephalus
B ) Large or multiple axial nevi
C ) Posterior midline nevi
D ) €œSatellite € nevi
E ) Underdevelopment of a limb
The correct response is Option A.
This patient has congenital melanocytic nevi (CMN), which are birthmarks that are present at birth or become apparent within the first year of life. They are found in 1% to 2% of the general population. In addition to being cosmetically disfiguring, CMN are one of several known risk factors for development of melanoma.
While the majority of malignant melanomas arise from melanocytes in previously normal skin or within acquired and often atypical (dysplastic) melanocytic nevi, few would dispute the contention that melanomas may arise in CMN. The incidence of such malignant transformation, however, remains a highly controversial topic in cutaneous oncology. It has been estimated that large CMN carry a 4.5% to 10% lifetime risk of melanoma or other neural crest malignancies. While this risk appears to be distributed over the lifetime of the patient, recent studies suggest that it is greatest in early childhood, between birth and 10 years of age, with 50% of the malignancies developing by 5 years of age, and 70% by 10 years of age. Interestingly, 50% of the melanomas that develop occur within the nevi, but the other 50% occur within the central nervous system (CNS) or within normal skin. Despite this significant increase in risk, it should be noted that giant CMN-associated melanomas still account for less than 3% of all pediatric melanomas.
Large CMN may also be associated with symptomatic or asymptomatic systemic abnormalities. Whereas melanocytes in CMN are generally limited to the mid to upper dermis, a subset of giant CMN exhibit melanocytes in the lower third of the dermis, within the subcutaneous fat, and occasionally as deep as the fascia and skeletal muscles possibly causing ipsilateral limb underdevelopment. Large axial CMN have been associated with the syndrome of neurocutaneous melanosis (NCM).
NCM connotes the association of a large axial CMN with the CNS involvement. CNS manifestations may present as hydrocephalus, seizures, focal deficits, or partial paresis. The majority of those children with NCM who manifest such problems do so before 2 years of age. When neurologic symptoms are present, the prognosis is grave. At least two thirds of those who present with or develop symptomatic CNS disease succumb to the disease process, either because of inexorable €œbenign € proliferation of melanocytes in the leptomeninges and brain or as a result of malignant degeneration. Symptomatic hydrocephalus may necessitate the placement of a ventriculoperitoneal or ventriculojugular shunt. Unfortunately, following malignant transformation in the CNS, such shunts afford the malignant melanocytes ready access to the systemic circulation, leading to a rapid demise.
To identify which patients with CMN may have CNS involvement, a number of risk factors have been identified. These include the presence of large or multiple axial CMN or both, nevi on the posterior midline, and the presence of multiple satellite nevi. MRI with gadolinium contrast has proved to be a particularly sensitive method for detecting the presence of CNS involvement by melanocytes in such patients. MRI can detect occult neurologic involvement even in infants who are clinically normal. In addition to meningeal involvement, lesions in the cerebrum, cerebellum, spinal cord, and elsewhere have been detected. The ultimate significance of such radiologically evident lesions in clinically asymptomatic children remains to be determined. The risk of developing NCM must also be a factor in any treatment decision, as the prognosis for children with symptomatic NCM is extremely poor. Since the majority of patients with NCM will succumb to the CNS involvement and not from the nevi themselves, it may be determined that the risk of surgical removal of giant CMN in these patients outweighs the benefits.
In certain children at high risk for the development of NCM (eg, those with large CMN in a posterior axial location in the presence of satellite nevi), and especially in those children with radiologic evidence of CNS involvement, a delay in surgical treatment of the large CMN until 2 years of age (the median age for presentation of neurologic symptoms) might be considered. The prognosis for children with symptomatic CNS involvement is so poor that most are unlikely to survive long enough to succumb to the €œrelatively € low risk of cutaneous melanoma.
