2-15 Benign Neoplastic Lesions of Skin and Disorders of Pigmentation Flashcards
Explain the Fitzpatrick scale.
I Pale, light hair +/- freckles Burns very easily
II Light skin and hair Usually burns
III Creamy skin, any hair color Tans well +/- burns
IV Light brown (Mediterranean) Tans well, rarely burns
V Medium brown Tans well, rarely burns
VI Deep brown Very rarely burns
What falls under the heading of benign neoplastic lesions of skin and disorders of pigmentation?
I.Benign epithelial tumors
A.Fibroepithelial polyp
B.Epithelial inclusion cyst
C.Seborrheic keratosis
II.Adnexal neoplasms
III.Dermal tumors
A.Hemangioma
B.Xanthoma
C.Dermatofibroma (fibrous histiocytoma)
IV.Disorders skin pigmentation, macular or patch type
V.Acanthosis nigricans
VI.Tattoos
VII.Benign melanocytic neoplasms, nevocellular nevi
A.Junctional, compound, intradermal nevi
B.Blue nevus
C.Dysplastic nevus
What are FEPs/Fibroepithelial polyps?
•Also known as
–skin tags
–acrochordon
–fibroma molle
–squamous papilloma
–
- Occur in individuals usually age 30 or greater and particularly in obese individuals
- Associated with areas of rubbing by clothing; collar of neck or groin
- Has vascular supply and variable stroma from fatty to fibrous
What is an epithelial inclusion cyst?
- Also known as an epidermal cyst, follicular infundibular cyst or a wen
- Occur where there are large numbers of hair follicles (face, scalp, trunk)
- Caused by obstruction of hair follicle at infundibulum (near where hair shaft extends beyond skin surface)
- Filled with keratinous debris
- Lined by squamous epithelium with a granular cell layer
–A similar cyst, but without a granular cell layer is the trichilemmal/pilar cyst
•If ruptured (trauma) →
foreign body granulomatous giant cell inflammatory reaction to the keratin debris and pain
What is a trichilemmal cyst?
Epidermal cyst
A similar cyst, but without a granular cell layer is the trichilemmal/pilar cyst
Caused by obstruction of hair follicle at infundibulum (near where hair shaft extends beyond skin surface)
Filled with keratinous debris
What is seborrheic keratosis/SK?
- Proliferation of epidermal basal cells
- Usually middle-aged or older
- “Postage stamp” appearance, can look like melanoma
- Round, flat but elevated, can have keratin popping out of pseudocysts
- On non-exposed skin (trunk, proximal extremities, lateral neck)
- Many have mutations in fibroblast growth factor receptor 3
- Removed for cosmetic reasons or because lesion may resemble a malignant melanoma
- Sign of Leser-Trélat – acute onset of SKs with malignancies (GI mostly)
What is sign of Leser-Trelat?
Acute onset of SK/seborrheic keratosis with malignancies (GI mostly)
What are adenxal neoplasms? Discuss origins, and benign versus malignant.
- Overwhelming majority (99%) are benign
- Arise from the ductal and glandular epithelial cells of adnexa
–Sweat glands & ducts; hair-bulb germinal epithelium and sebaceous glands; apocrine glands and ducts
- Benign adnexal tumors are
- Symmetrical, small (<1 cm), superficial, vertically orientated
- Malignant adnexal tumors are
- Asymmetrical, large, deep, wide
–Sebaceous carcinoma
•Most common type of malignant adnexal neoplasm, but quite uncommon
–Eccrine carcinoma
–Apocrine carcinoma
What are the names of some adnexal neoplasms? Discuss some histo findings too.
Sebaceous adenoma/carcinoma
Look for foamy cytoplasm, noting sebum
Malignant cells are invasive and push into other cells
Pilomatrixoma
tumor of matrix of the hair follicle
no granular cell layer
Ghost cells undergo apoptosis
Apocrine Hydrocystoma
cyst with fluid in skin, lining with apocrine epithelium – fibrocystic change, anything that is apocrine has more fibers
can also have accrine hydrocystoma
Where do cylindromas and trichoepitheliomas occur?
Cylindroma – nests of basaloid cells that look like jigsaw puzzles on forehead and scalp
Trichoepithelioma – full of hair shafts – tumor arising from hair follicle, looks like epitheliod basaloma
Both look like little tiny bumps
What adnexal tumors arise from the hair follicles? What are the histologic features and clinical significance?
Trichoepithelioma
Trichofolliculoma
Tricholemmoma
Pilomatricoma
Histologic features:
Hair matrix, outer root sheath differentiation
Clinical significance:
Cowden syndrome: Multiple tricholemmomas with dominant inheritance
What adnexal tumors arise from the sebaceous glands? What are the histologic features and clinical significance?
Sebaceous adenoma
Sebaceous epithelioma
Histo: Cytoplasmic lipid vacuoles
Clinical:
Muir-Torre Syndrome: sebaceous adenomas with association colorectal malignancy (variant of Lynch)
What adnexal tumors arise from apocrine glands? What are the histologic features and clinical significance?
Syringocystadenoma papilliferum
histo: Apocrine type “decapitation” secretion
Clinical: May develop in mixed epidermal-adnexal hamartomas of face and scalp termed nevus sebaceous
What adnexal tumors arise from eccrine glands? What are the histologic features and clinical significance?
Syringoma
(lower eyelids)
Cylindroma
(forehead and scalp)
Poroma
(palmar or plantar regions)
histo: Eccrine ducts lined by membranous eosinophilic cuticles; tadpole-like epithelial structures
Clinical: may be confused with basal cell carcinoma clinically
Turban tumor :
Massive confluent cylindromas (basal cell origin)
What are the dermal ‘lumps and bumps’?
- Hemangioma - Red
- Xanthomas – Yellow
- Fibrohistiocytic lesions – normal tan-brown skin tone or darker (darker d/t fibrocystic or reactive change in pigmentation over the top of them.)
These are from the deeper layers - the dermis, from mesenchyme.
What do hemangiomas look like on gross and histo?
gross: well vascularized papules/macules, reddish to reddish brown in color
histo:
cavernous has more big open spaces
Lobular is more common, if ulcerated, inflamed and full of neutrophils it can be a pyogenic granuloma
What do xanthomas look like on gross and histo?
gross: yellowish papules
histo: macrophages full of lipid, large cells with clear/slightly foamy cytoplasm
What is a benign fibrous histiocytoma?
AKA dermatofibroma
Benign
In adults, frequently on the legs of young – middle aged women
Tan-brown, usually <1.0 cm
May occasionally be tender
(Benign and full of big bundles of fibrogenous tissue
- tend to push everything away (unlike neurofibromas, which encircle things)
Can cause hyperplasia of epithelium overlying it)
What are some benign skin pigment disorders?
•Increased melanin in keratinocytes: NO increase in number of melanocytes
–Sun tan
–Freckles
–Café au lait spots
–Melasma
•Increased melanin in keratinocytes: small increase in number of melanocytes
–Solar lentigo
•Loss of Melanin in keratinocytes
–Acute transient vitiligo
–Albinism
•Loss of Melanocytes
–Chronic vitiligo
•Acquired Pigmentation
–Skin tattoo
–Amalgam tattoo
What is a suntan?
- Due to ultraviolet light exposure
- UVB exposure →
–Melanocyte melanosome production →
–Increased melanin per keratinocyte→
–Increased protection against solar radiation (mid-UV [UVB] spectrum)
•Chronic skin damage and neoplasia also induced by exposure to ultraviolet radiation
(Tan is a protective mechanism/irritation for skin, to protect skin from UVB damage)
What are the benign hypermelanosis abnormalities?
Freckles - Ephelides (sounds like an elf from LOTR)
Cafe au Lait spot
Hypermelanosis in both abnormalities
Small spots = freckles
Large area = café au lait spot
(Both represent an increase in melanin, become more prominent with sun exposure.
Mult café au lait spots – worry about Neurofibromatosis type I)
What is found in neurofibromatosis Type I?
- Autosomal dominant disorder
- NF1 gene mutation that blocks encoding of neurofibromin (RAS inhibitor)
- Neurofibromas (including plexiform)
–Can develop malignant nerve sheath tumors
- Café au lait spots (macules)
- Freckles in axilla
- Optic nerve gliomas
- Lisch nodules on iris
(melanotic hamartomas)
- Macrocephaly
- Scoliosis
What is found in neurofibromatosis Type II?
Type 2 has bilateral acoustic nerveSchwannomas , CNS gliomas
(ependymomas of spinal cord),
and cataracts
What is chloasma?
Melasma
- A.K.A. “Mask of Pregnancy” and “Chloasma”
- Blotchy hypermelanosis on face
–Symmetrical distribution over the cheeks and forehead
–Less frequently on upper lip and neck
- Appears in women>>>men
- Occurs: (due to estrogen)
–During pregnancy
–In women taking oral contraceptives
–At menopause
What is acanthosis nigricans?
•Epidermal hyperplasia of stratum spinosum & hyperpigmentation
•Prefers flexural regions
–axillae, skin folds of neck, groin and anogenital regions
•80% occur with benign conditions
–Autosomal dominant forms with variable penetrance
•Onset during childhood or puberty
–Also occur with obesity or endocrine abnormalities
•20% are paraneoplastic
–Malignancy (adenocarcinoma) signals the epidermis to undergo epidermal hyperplasia.
–Arises in middle-aged and older individuals
What is a tattoo?
Tattoo = Acquired Pigmentation
May be intentional or incidental (pencil “lead” breaking in skin or oral amalgam injury)
May mimic pigmented lesions such as nevi and melanoma if incidental
May “bleed” if pigment travels in dermis or as macrophages move
Will fade over time as melanocytes move deeper into dermis and out of dermis
What is solar lentigo?
AKA Lentigo Senilis, Lentigo Simplex
•Benign, discrete hyperpigmented macule on chronically sun exposed skin
–Back of the hands and the forehead in adults
- Variable increase in number of junctional melanocytes & increased melanin pigment in keratinocytes
- Note: “lentigo or lentiginous” means a proliferation of melanocytes
–Lentigo maligna is the name given to an in situ melanoma arising in sun exposed skin
What is macular/patch skin depigmentation?
•Loss of melanin in keratinocytes
–Acute transient vitiligo
•e.g. keratinolytic agents that remove layers of pigmented keratinocytes
–Albinism
- Defect in tyrosinase, an enzyme necessary for melanin production
- Permanent lack or loss of melanocytes
–Chronic vitiligo
(Skin pigment is in keratinocytes, so if you slough off skin you can get acute transient vitiligo.
- acute vitiligo – loss of skin
- chronic vitiligo – loss of melanocyets
Albinism – usu problems with tyrosine metabolism – photophobia, difficulty seeing)
What are melanocytic/nevocellular nevi?
•Neoplastic nested melanocyte proliferation (clusters)
–Junctional: Basal epidermal nests
•Maculopapular
–Compound: Basal epidermal and dermal nests
•Papular
–Intradermal: Dermal nests
- Papular to nodular
- Acquired mutations in NRAS and BRAF are commonly found
–Mutations induce melanocyte neoplasia short of malignancy
What is the postulated natural history of nevi?
Stage I
Junctional nevus, with nests of melanocytes along base of epidermis
Stage II
Compound nevus, with nests of melanocytes at base of epidermis and dermis
Stage III
Intradermal/Dermal nevus, with nests of melanocytes present only in the dermis
Stage IV
Neurotized nevus, with melanocytes changing appearance from epitheliod to spindled shape (looks less like epithelium and more like neural tissue)
What is a congenital nevus?
- Present at birth (birthmark)
- Benign, but melanoma can arise in the larger congenital nevi
- Extensive deep dermal to subcutaneous growth with proliferative nodules
What is a blue nevus?
- Intradermal, roughly wedge-shaped and slightly raised skin surface
- Thin, delicate melanocytes in a dense reactive fibrotic stroma
- Melanin pigment in melanocytes, melanophages, or other adjacent structures cause the bluish color
- Benign with no significant risk for development of melanoma
What is a Spitz nevus?
Spitz nevus - AKA spindle & epitheliod cell nevus
- Usually in children and young adults
- Can be red like hemangioma or pigmented and can clinically & histologically mimic a melanoma (and melanomas can look like Spitz nevi)
- Characteristic raining down melanocyte pattern and Kamino bodies (eosinophilic amorphous globules)
What is a halo nevus?
•Involuting (regressing) nevus with extensive lymphocyte infiltration and depigmentation of surrounding skin
