Sec 22 Melanocytic Tumors Flashcards
Presence of melanocytic cells in epidermal nests, defined as three or more melanocytic cells in direct contact (also known as thèque), within the dermis, or in other tissues
Melanocytic neoplasia
Increased melanocytes confined to the basal layer of the epidermis
Melanocytic hyperplasia
Represent a developmental abnormality of normal melanocytic development due to a mutation that occurs in a progenitor cell that results in the abnormal extensive accumulation of melanocytic cells along migration pathways during normal development
Congenital Nevomelanocytic Nevus
Present at birth but large variety appear between 1 month and 2 years of life, grows relatively proportionally, associated with loss of pigmentation, halo depigmentation, and regression
Congenital Nevomelanocytic Nevus
Congenital Nevomelanocytic Nevus: Small Medium Large Giant
Small <1.5 cm
Medium 1.5–19.9 cm
Large (≥20 cm)
Giant - as large as the patient’s palm if on the head and neck (and twice that area for other anatomic sites), 30% of the body surface, or 900 cm2 in adults
Have smooth, regular, and sharply demarcated border, and skin markings distort the skin surface; some relatively hairless; some have coarse, long, darkly pigmented; have a smooth, pebbly, rugose, verrucous, cerebriform, or grossly lobular surface
Congenital Nevomelanocytic Nevi
CNNs of the head, neck, or posterior midline, and/or the presence of multiple satellite lesions associated with large CNN may be complicated
Cranial and/or spinal leptomeningeal melanocytosis
Associated with giant CNN
Neurofibromatosis
Associated with the relatively sudden appearance of a dermal or subcutaneous nodule, very dark pigmentation, itching, pain, bleeding, or ulceration
Malignant degeneration of large CNNs
Histopathology: presence of nevomelanocytes in the epidermis as well-ordered thèques and/or nevomelanocytes in the dermis, which are present as sheets, nests, cords, and/ or single cells
Congenital Nevomelanocytic Nevus
Histopathology: appearance may be identical to typical acquired nevi, with nevomelanocytes in the epidermis as well-defined thèques and/or nevomelanocytes in the papillary dermis as sheets, cords, or nests; nevomelanocytes in the lower two-thirds of the reticular dermis and to be associated with appendageal and neurovascular structures
Nevomelanocytic type of large CNN
Histopathology: melanocytic elements take on the appearance of Wagner-Meissner corpuscles (lames foliacée), a palisaded arrangement of cells around a cellular mass of homogeneous material (Verocay body), and sheathing of nerves by neuroid tissue (neuroid tubes); may be responsible for lobulation and redundancy of tissue (pachydermatous or cerebriform appearance) due to the production of connective tissue elements such as reticulin, collagen, and sometimes mucinous stroma; may take on the appearance of a pigmented neurofibroma
Neuroid type of giant CNN
Histopathology: dermis may be infiltrated in whole or in part by nests or sheets of epithelioid cells and/or spindle cells; may have atypical cellular and architectural features, large epithelioid cells may comprise superficial papillary zones of the nevus, and smaller nevomelanocytes may appear in the same lesion in deeper zones of the reticular dermis, with a grenz zone separating the two elements
Spindle cell and/or epithelioid cell type of giant CNN
Histopathology: appearance may be that of a giant blue nevus, or the lesion may have elements of blue nevus (either common or cellular type) with heavily pigmented spindle-shaped melanocytic cells alone or intermixed with nevomelanocytes in the reticular dermis or deeper tissues
Blue (dermal melanocytic) type of giant CNN
Treatment goal in CNN
To remove as much of the nevus while preserving function and improving cosmetic appearance
Presents as a circumscribed macule/patch of tan background pigmentation (<1 cm to >10 cm in diameter) with features consistent with lentigo or café-au-lait macules including scattered, more darkly pigmented nevomelanocytic (or more hyperplastic) macular and/or papular elements
Nevus spilus
Associated with large varieties of nevus spilus
Multiple granular tumors Nevus flammeus Muscle atrophy Neurological disorders Phacomatosis pigmentokeratotica
Histopathology: consists of increased numbers of melanocytes in a lentiginous epidermal pattern
Electron microscopy: demonstrate melanin macroglobules
Nevus spilus - tan background pigmentation
Histopathology: demonstrate foci of increased melanocytic hyperplasia or melanocytic dysplasia (architectural disorder and variable cellular atypia)
Nevus spilus - flat, dark elements
Histopathology: usually contain collections of nevomelanocytes in the epidermis and/or dermis
Nevus spilus - raised elements
Develop after birth, slowly enlarge symmetrically, stabilize, and after a period of time may regress with majority develop during the 2nd-3rd decades of life
Common acquired nevomelanocytic nevi
Spontaneous and concurrent development of scattered nevomelanocytic nevi often similar in appearance
Eruptive nevi
Phenomenon of spontaneous development of a zone of depigmentation around a preexisting nevus, indicating the onset of involution and subsequent regression
Halo nevus Leukoderma acquisitum centrifugum Sutton’s nevus Leukopigmentary nevus Perinevoid vitiligo Perinevoid leukoderma
Lesions have a homogeneous surface and coloration pattern, round or oval shape, regular outlines, and relatively sharp borders; may be papillomatous, dome-shaped, pedunculated, or flat-topped and are usually skin-colored, pink, or brown
Common acquired nevomelanocytic nevi
May cause redness and even blistering in the perinevic halo
UV radiation
Process that results in the development of an eczematous dermatitis presenting as a red halo around nevi but no regression
Halo dermatitis
Meyerson’s nevus
Most common associated condition in halo nevus occurring in 18% to 26% of patients
Vitiligo
Associated with halo nevus
Poliosis Vogt-Koyanagi-Harada syndrome Pernicious anemia Prominent numbers of nevi Atypical nevi Personal or family history of melanoma
Relatively large number or numerous nevi are seen in
Turner syndrome
Noonan syndrome
Eruptive nevi suggests
Blistering disease
Immunosuppression
Nevomelanocytes in the deep dermis may be disposed within a collagenous framework that is loose, pale, and wavy in formations called
Neuroid tubes
Composed of peculiar foam cells comprising a portion or all of a given lesion; multinucleated balloon cells and multinucleated giant cells are seen frequently
Balloon cell nevus
Refers to the incontiguity association of different types of melanocytic nevi; most found in association with a benign compound nevus
Combined nevus
Name given to recurrent lesions after incomplete removal of a benign nevomelanocytic nevus; common after superficial destructive procedures
Recurrent melanocytic nevus
Histopathology: central nevomelanocytic nevus associated with a dermal band-like lymphohistiocytic infiltrate and a depigmented zone totally or almost totally devoid of epidermal melanocytes
Halo nevus
Useful in discriminating benign lesions from lesions with a metastatic tendency
FISH (fluorescence in situ hybridization)
CGH (comparative genomic hybridization)
In nevi, may help confirm a benign diagnosis
Low Ki67 activity and loss of HMB45 in dermal (deeper) cells
Associated with multiple blue nevi
Lentigines, cardiac myxoma, and mucocutaneous myxomas
[Carney complex/LAMB syndrome (Lentigines, Atrial myxomas, Mucocutaneous myxomas, and Blue nevi)]
Derived from a mutant precursor cell resulting in the accumulation and differentiation of the melanocytic cells in the dermis
Blue nevus
Mutation in blue nevus
GNAQ gene
Usually acquired, and once developed remain stable usually solitary, asymptomatic blue, blue-gray, or blue-black papules, usually less than 10 mm in diameter occur anywhere, but about half are present on the dorsa of hands and feet
Blue nevus
The blue-gray color of blue nevi is an optical effect of blue light backscatter from the skin over the dermal melanin
Tyndall effect
Associated with large plaque blue nevus (pilar neurocristic hamartoma)
Lentigo simplex
Darkly pigmented, blue-black papules or nodules, mostly on the head and neck or upper extremities, 2–9 mm in diameter, and occurring predominantly in the 1st four decades of life, including childhood
Deep penetrating nevi
Blue-gray or blue-brown nodules or plaques 1-3 cm in diameter, occasionally larger with surface usually smooth but may be irregular; one-half the cases are located on the buttocks or sacrum and may develop in association with CNN; more elevated, more aggressive locally, and occasionally associated with lymph node “benign metastasis”
Cellular blue nevi
Presents as an expanding dermal nodule with or without ulceration and may develop in contiguity with a cellular blue nevus, nevus of Ota, combined congenital blue nevus, or de novo
Malignant blue nevus (melanoma)
Histopathology: dermal melanocytes appear as melanin-containing fibroblast-like cells grouped in irregular bundles admixed with melanin-containing macrophages, associated with excessive fibrous tissue in the middle or upper reticular dermis, occasionally extending downward to subcutaneous fat or upward to papillary dermis; elongated melanin-producing dermal melanocytes lie with their long axis parallel to the epidermis
Common blue nevi
Histopathology: peripilar grouped arrangement of mostly spindle cells containing varying amounts of melanin, patterns of a common blue nevus and dermal melanocytosis (Mongolian spot), and presence of abnormal (granular) melanosomes
Plaque-like blue nevus (pilar neurocristic hamartoma)
Histopathology: may have both spindle and epithelioid cell forms and demonstrates deep extension into the dermis or subcutis in a wedge-shaped structure potentially tracking with neurovascular or adnexal structures
Deep penetrating nevi
Histopathology: a component of a common blue nevus plus fascicles of spindle-shaped cells with ovoid nuclei and abundant pale cytoplasm with little or no melanin, and often epithelioid cells, present in the dermis and often in subcutaneous fat in nests, bundles, and neuroid forms with little or no intervening stroma
Cellular blue nevi
Major complication of blue nevi
Potential risk of melanoma (highest - cellular blue nevus)
Common blue nevus that would require histopathologic examination
Sudden appearance of blue nodule
Expansion of a pre-existing blue nodule
Congenital blue nodule
Relatively large blue nodule or plaque >10mm in diameter
Acquired lesions, often during the third decade of life presents as sharply circumscribed, uniformly darkly pigmented papule
Pigmented spindle cell nevus
Dermoscopy: diffusely jet black with a sharp well defined border - should interface with the skin in a similar (uniform) manner for the full circumference of the lesion; pattern is often “starburst” in appearance
Pigmented spindle cell nevus
Histopathology: consists of vertically oriented fascicles of spindle-shaped, pigment-producing melanocytes; some pagetoid upward migration may be present, but the lesion can be distinguished from melanoma by uniform nuclei, uniform cellular detail, and distinctive pattern of growth; most cases have a lymphohistiocytic host response
Pigmented spindle cell nevus
Treatment: Pigmented spindle cell nevus
Excision with 3-5mm margin of normal skin
Dermoscopy: oval, uniform, and gray-blue in color; some have a central amorphous yellow appearance
Blue nevus
Presents most commonly as a solitary, asymptomatic, pink or red, hairless, firm, and dome-shaped; some may resemble a keloid with commonly smooth surface, and the borders may fade into surrounding skin; usually asymptomatic, but pruritus, tenderness, and/or bleeding may occur
Spitz nevus