Skin Pathology Flashcards
What is the most common pigmented lesion of childhood in lightly pigmented people?
Freckle
What leads to a lentigo?
A localized melanocytic hyperplasia.
What are nevus cells?
A form of a melanocyte - the pigment-producing cells that colonize the epidermis.
Congenital melanocytic nevi are thought to represent what?
Most acquired melanocytic nevi are considered what?
Possible anomaly in embryogenesis.
Benign cellular aggregates.
What is a dysplastic nevus?
A coalescent intradermal nest with cytologic atypia that may be a marker or precursor of melanoma.
What is another term for “mole”?
Melanocytic nevus.
Melanocytic nevi may arise due to what mutations in which pathway?
Mutations in the Ras pathway.
What are seborrheic keratoses?
Common benign tumors found on the trunk of middle-aged or elderly patients.
What is the gross morphology of seborrheic keratoses?
Superficial/flat and appear coin-like with waxy exophytic lesions. They may have a velvety surface.
What mutation may be found in sporadic seborrheic keratoses?
In what other skin tumor might this mutation exist?
Activating mutation in FGFR3.
Acanthosis nigricans.
What is the appearance of acanthosis nigricans?
Dark-thickened skin in creases or flexural areas with a velvety texture.
What percent of acanthosis nigricans is benign vs. associated with malignancy?
80% benign.
- acquired: obesity, DM, pineal tumor, pituitary tumor, autoimmune endocrinopathy.
- inherited: rare, AD inheritance.
20% associated with malignancy: solid tumors, mostly GI carcinomas.
What is another term for a fibroepithelial polyp?
“Skin tag”.
What causes an epithelial inclusion cyst (wen)?
What is another name for it?
Invagination and cystic expansion of the epidermis, or from a hair follicle.
Sebaceous cyst.
What are 5 examples of adnexal (appendage) tumors?
Eccrine poroma
Cylindroma
Syringoma
Sebaceous adenoma
Pilomatricoma
Where do eccrine poromas occur?
Palms and soles - where sweat glands are numerous.
What is a cylindroma?
What is a turban tumor?
An adnexal tumor with ductal differentiation on the forehead and scalp.
A turban tumor develops when there is coalescence of nodules with time that produces a hat-like growth.
What are syringomas?
Lesions with eccrine differentiation, usually occurring in multiples near the eyelids.
Sebaceous adenomas are association with which hereditary non-polyposis colorectal carcinoma syndrome?
Muir-Torre syndrome.
What is actinic keratosis?
What is their appearance?
Areas of sun-damaged skin with hyperkeratosis. They may be a precursor to malignancy.
They are usually less than 1 cm. in diameter and are reddish-brown with a sandpaper-like consistency. Some lesions may even develop a “cutaneous horn”.
Actinic keratosis associated with which mutations?
TP53 mutations.
What are the 2 major associations with squamous cell carcinoma?
Sunlight exposure - UV radiation.
Immunosuppression - increases likelihood of infection with HPV-5 and HPV-8.
What is epidermodysplasia verruciformis?
A rare AR condition with a high susceptibility to cutaneous squamous cell carcinoma due to infection with HPV-5 and HPV-8.
What is xeroderma pigmentosum?
A genetic disorder in which there is a decreased ability to repair DNA damage such as that caused by UV light. It increases one’s risk for squamous cell carcinoma.
What is the “most common invasive cancer in humans”?
Basal cell carcinoma.
What is the course/aggressiveness of basal cell carcinoma?
What mutation is classically involved?
They are slow-growing that rarely metastasize. The are often recognized early and excised.
Constant activation of Hedgehog signaling.
What syndrome is associated with multiple basal cell carcinomas, (medulloblastomas or ovarian fibromas), odontogenic keratocysts and pits on palms/soles?
Gorlin syndrome (AKA nevoid basal cell carcinoma syndrome (NBCCS)).
What are the most common “driver” mutations in melanoma? (3)
Cell cycle control: CDKN2A gene (encodes p15, p16 and p14).
Pro-growth mutations: RAS and PI3K/AKT signaling.
Telomerase: TERT.
What is the gross appearance of melanoma?
What type of growth is noted?
They have variations in color and have irregular borders that are often notched.
Radial growth describes the horizontal spread of melanoma in epidermis and superficial dermis.
What is the ABCDE rule?
It is a guide to the usual signs of melanoma.
A - asymmetry. B - border is irregular. C - color is not uniform. D - diameter > 6 mm. E - evolving features.
What is the mnemonic for “painful” skin lesions?
GLENDAB
G - glomus tumor. L - leiomyoma (angio-type). E - eccrine spiradenoma. N - neurofibroma. D - dermatofibroma. A - angiolipoma. B - blue rubber bleb nevus.
What are the layers of the epidermis (superficial to deep)? (5)
“Come, let’s get sun burned!”
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
What is a dermatofibroma (benign fibrous histiocytoma)?
What often occurs prior to the development of this tumor?
A benign tumor found in adults and in the legs of young and middle-aged women. The lesion may be asymptomatic or tender and may change slightly in size over time.
Often preceded by trauma, which suggests an abnormal response to injury and inflammation.
What is dermatofibrosarcoma protuberans?
What is the hallmark genetic change?
A well-differentiated primary fibrosarcoma of the skin. They are slow-growing, but may be locally invasive, however they rarely metastasize.
A translocation involving the genes encoding colagen 1A1 (COL1A1) and platelet-derived growth factor-B (PDGFB).
What is mycosis fungoides?
When does it generally occur?
A type of cutaneous T-cell lymphoma that is usually confined to the skin for years, but potentially may evolve into a systemic lymhoma.
It can occur at any age, but most commonly in patients > 40 y/o.
What is the gross appearance of mycosis fungoides?
The proliferating cells are what type?
Scaly, red-brown patches with raised, scaling plaques which can be confused for psoriasis.
CD4+ T-cells.