Skin + Bone and Joints

Desmosomes

What are the cell junctions that glue squamous epithelial cells together?

Melanocytes

Which cells in the epidermis produce brown pigment to protect against UV radiation?

Melanin

What brown pigment absorbs and protects against potentially injurious UV radiation?

Dendritic cells

Which cells in the skin process antigens and present them to T lymphocytes in regional lymph nodes?

Cutaneous lymphocyte-associated antigen (CLA)

Which adhesion molecule is expressed by T cells that home back to the dermis?

Skin microbiome

What is the term for the normal "zoo" of organisms on the skin that prevents colonization by harmful ones?

Merkel cell

Which cell type in the epithelial basal cell layer has neuroendocrine or mechanoreceptor functions?

Sweat glands

Which skin adnexal components help to regulate body temperature?

Sebaceous glands

Which glands secrete sebum to lubricate skin and provide antimicrobial properties?

Hair follicles

Which adnexal structures harbor stem cells capable of regenerating superficial epithelial skin?

Excoriation

What is the macroscopic term for a traumatic lesion breaking the epidermis causing a deep scratch?

Lichenification

What is the macroscopic term for thickened, rough skin resulting from repeated rubbing?

Macule

What is a circumscribed flat lesion less than 10 mm in diameter?

Patch

What is a circumscribed flat lesion greater than 10 mm in diameter?

Papule

What is an elevated dome-shaped or flat-topped lesion less than 10 mm across?

Nodule

What is an elevated dome-shaped lesion greater than 10 mm in size?

Plaque

What is an elevated flat-topped lesion usually greater than 10 mm across?

Pustule

What is a discrete pus-filled raised lesion?

Scale

What is a dry, horny, plate-like excrescence resulting from imperfect cornification?

Vesicle

What is a fluid-filled raised lesion 10 mm or less across?

Bulla

What is a fluid-filled raised lesion greater than 10 mm across?

Wheal

What is an itchy, transient, elevated lesion with variable blanching and erythema formed by dermal edema?

Acanthosis

What is the microscopic term for diffuse epidermal hyperplasia?

Dyskeratosis

What is the microscopic term for abnormal, premature keratinization below the stratum granulosum?

Erosion

What describes a discontinuity of the skin showing incomplete loss of the epidermis?

Exocytosis

What is the infiltration of the epidermis by inflammatory cells called?

Hydropic swelling

What is intracellular edema of keratinocytes, often seen in viral infections, also called?

Hypergranulosis

What is hyperplasia of the stratum granulosum often due to intense rubbing?

Hyperkeratosis

What is the thickening of the stratum corneum often associated with qualitative keratin abnormalities?

Lentiginous

What is a linear pattern of melanocyte proliferation within the epidermal basal cell layer?

Papillomatosis

What is a surface elevation caused by hyperplasia and enlargement of contiguous dermal papillae?

Parakeratosis

What is keratinization with retained nuclei in the stratum corneum?

Spongiosis

What is intercellular edema of the epidermis?

Ulceration

What is a complete loss of the epidermis revealing the dermis or subcutis?

Vacuolization

What is the formation of vacuoles within or adjacent to cells, often in the basal cell-basement membrane zone?

Ephelis

What is the medical term for a freckle?

Lentigo

What is a small tan-brown macule caused by linear melanocytic hyperplasia above the basement membrane?

RAS pathway

Melanocytic nevi are common benign neoplasms strongly associated with acquired activating mutations in which signaling pathway?

CDKN2A

Which gene encodes p16 and is frequently lost in the development of melanoma?

p16

What potent inhibitor of CDK4 and CDK6 mediates permanent growth arrest in nevi?

Junctional nevus

What is the earliest morphologic stage of a nevus, consisting of aggregates along the dermoepidermal junction?

Compound nevus

What type of nevus combines features of junctional nests with nests and cords of dermal nevus cells?

Intradermal nevus

What type of nevus has lost its epidermal nests entirely?

Neurotization

What is the striking metamorphosis of deeper nevus cells into fusiform fascicles resembling neural tissue?

Dysplastic nevus syndrome

What autosomal dominant disorder is characterized by a tendency to develop multiple dysplastic nevi and melanoma?

Lentiginous hyperplasia

What microscopic process involves single nevus cells replacing the normal basal cell layer along the dermoepidermal junction?

Melanin incontinence

What term describes the release of melanin from dead nevus cells into the dermis, where macrophages phagocytose it?

Upper back in males

What is the most common sun-exposed site for melanoma in males?

Back and legs in females

What is the most common sun-exposed site for melanoma in females?

BRAF

Activating mutations in which serine/threonine kinase are seen in 40 to 50 percent of melanomas?

TERT

Sequencing of sporadic melanomas has identified mutations in the promoter of which gene that encodes the catalytic subunit of telomerase?

Radial growth phase

What describes the initial horizontal spread of melanoma within the epidermis and superficial dermis?

Vertical growth phase

What phase of melanoma involves downward invasion into the dermis as an expansile mass with metastatic potential?

Sentinel lymph node biopsy

What procedure is used to obtain additional prognostic information about the metastatic spread of melanoma?

Asymmetry

What does the A stand for in the ABCDEs of melanoma clinical features?

Diameter

What does the D stand for in the ABCDEs of melanoma clinical features?

FGFR3

Activating mutations in which receptor tyrosine kinase are found in many sporadic seborrheic keratoses?

Leser-Trelat sign

What is the sudden appearance of seborrheic keratoses in large numbers as part of a paraneoplastic syndrome?

Horn cysts

What are small keratin-filled cysts characteristic of seborrheic keratosis?

Dermatosis papulosa nigra

What condition presents as multiple small dark brown to black seborrheic keratoses on the face of African Americans?

Flexural areas

Acanthosis nigricans most commonly appears in which body areas?

Gastrointestinal adenocarcinoma

Paraneoplastic acanthosis nigricans is most commonly associated with which cancer?

Skin tag

What is the colloquial term for a fibroepithelial polyp?

PTEN

Cowden syndrome is caused by germline mutations in which tumor-suppressor gene?

CYLD

Familial cylindromatosis is associated with germline inactivating mutations in which gene?

Turban tumor

What is the nickname for a cylindroma of the scalp?

Syringoma

Which lesion with eccrine differentiation usually occurs as multiple small papules near the lower eyelids?

Pilomatricoma

Which tumor with hair follicle differentiation is associated with activating mutations in CTNNB1?

Meibomian glands

Sebaceous carcinoma of the eyelid arises from which specific glands?

Actinic keratosis

What lesion occurs in sun-damaged skin, exhibits hyperkeratosis, and is a precursor to SCC?

Cutaneous horn

What structure can develop when actinic keratoses produce excessive keratin?

Squamous cell carcinoma

What is the second most common tumor arising on sun-exposed sites in older people?

Xeroderma pigmentosum

Which disorder involves a remarkable susceptibility to SCC due to an inability to repair pyrimidine dimers?

Hedgehog

Basal cell carcinoma is associated with mutations that activate which signaling pathway?

PTCH

Nevoid basal cell carcinoma syndrome is caused by a germline loss-of-function mutation in which gene?

Sonic hedgehog (SHH)

The PTCH protein is a receptor for which ligand?

Rodent ulcers

What archaic designation refers to advanced basal cell carcinomas with extensive local invasion?

Palisading

What term describes the radial arrangement of cells at the periphery of basal cell carcinoma islands?

Merkel cell virus (MCV)

Which virus is associated with the majority of Merkel cell carcinomas?

Dermatofibroma

What is the most common form of benign fibrous histiocytoma?

Pseudoepitheliomatous hyperplasia

What is the term for the peculiar overlying epidermal hyperplasia seen in dermatofibromas?

COL1A1 and PDGFB

Dermatofibrosarcoma protuberans is characterized by a translocation involving which two genes?

Storiform

What pinwheel-like alignment of spindled cells is characteristic of dermatofibrosarcoma protuberans?

Mycosis fungoides

What is the term for cutaneous T-cell lymphoma localized to the skin?

Pautrier microabscesses

What are small clusters of atypical T cells that invade the epidermis in mycosis fungoides?

Cerebriform

What contour describes the markedly infolded nuclear membranes of atypical lymphocytes in CTCL?

Urticaria pigmentosa

What is the cutaneous form of mastocytosis that affects predominantly children?

Darier sign

Which sign describes a localized wheal that occurs when mastocytosis lesional skin is rubbed?

Mast cell tryptase

An elevated serum level of which enzyme is a clue to the diagnosis of mastocytosis?

Ichthyosis

Which group of disorders is associated with fish-like scaliness due to excessive keratin buildup?

Steroid sulfatase

X-linked ichthyosis is caused by a deficiency in which enzyme?

Urticaria

What is the medical term for hives?

Type I hypersensitivity

Most urticaria is an example of which type of localized immediate reaction?

Hereditary angioneurotic edema

Which form of urticaria is caused by an inherited deficiency of C1 inhibitor?

Eczema

Which term is derived from the Greek word meaning "to boil over"?

Type IV hypersensitivity

Eczematous dermatitis typically results from which type of inflammatory reaction?

Haptens

In contact dermatitis, chemicals act as what by reacting with self proteins to create neoantigens?

Targetoid

What term describes the hallmark target-like lesions of erythema multiforme?

Stevens-Johnson syndrome

What is the febrile form of erythema multiforme often seen in children?

Toxic epidermal necrolysis

What variant of erythema multiforme is characterized by diffuse necrosis and sloughing of mucosal surfaces?