Ch. 3 - Malignant tumors of the epidermis Flashcards
Actinic keratosis
Crowded, disordered, and atypical epidermal keratinocytes arising from a broad-budding basal layer. Usually with solar elastosis. Can have overlying “malignant horn” of parakeratotic stratum corneum.
Acantholytic actinic keratosis
Crowded, disordeed, atypical epidermal keratinocytes with acantholysis in areas of atypia. Can have overlying “malignant horn” and complex epidermal budding.
Lichenoid actinic keratosis
Crowded, disordered, atypical epidermal keratinocytes with areas of lichenoid interface dermatitis. Can have overlying “malignant horn”.
Hypertrophic actinic keratosis
Crowded, disordered, atypical epidermal keratinocytes with acanthosis. Often has complex epidermal budding. Has prominent overlying “malignant horn”
Bowenoid actinic keratosis
Focal full-thickness atypia without anaplasia, nesting, buckshot scatter, or full-thickness follicular involvement.
Bowen’s disease
Full-thickness atypia with loss of normal maturation. Follicular involvement, atypical nests, intraepidermal buckshot, malignant horn.
*essentially squamous carcinoma in situ)
Distinguish between Bowen’s disease and Paget’s disease or melanoma.
In Bowen’s disease, the malignant keratinize can keratinize and become part of the stratum corneum.
Bowen’s disease is PAS+ (diastase sensitive) and CEA- while Paget’s is PAS+ (diastase resistant) and CEA+.
Squamous cell carcinoma
Atypical keratinocytes invading the dermis with acantholysis and desmoplasia. Look for nodular lymphoid aggregates. Do keratin immunostaining,
Verrucous carcinoma
Well-differentiated glassy eosinophilic squamous epithelium with blunt, rounded borders.
Spindled squamous cell carcinoma
(differential diagnosis?)
Atypical spindle cells abutting the epidermis.
SLAM: Squamous cell carcinoma, leiomyosarcoma, atypical fibroxanthoma, melanoma
Keratoacanthoma
Keratin-filled crater with invasive proliferation of glassy red keratinocytes. Neutrophilic & eosinophilic infiltrate. Hypergranulosis and pseudoepitheliomatous hyperplasia. Never acantholysis.
What is the natural history of keratoacanthomas?
Grow rapidly (especially after biopsy) and can involute spontaneously.
Distinguish between keratoacanthoma and squamous cell carcinoma.
Keratoacanthoma: Eosinophils and neutrophils. Central hypergranulosis and pseudoepitheliomatous hyperplasia. Terminal differentiation.
Squamous cell carcinoam: Plasma cells. Peripheral hypergranulosis and pseudoepitheliomatous hyperplasia. Invades eccrine glands.
Regressed keratoacanthoma
Crater filled with keratin and outlined by thin wall of involuted epithelium.
Basal cell carcinoma
Blue islands of basaloid cells with peripheral palisading. Retraction artifact and fibromyxoid stroma.
Superficial multifocal BCC
Multifocal blue buds with distinctive fibromyxoid stroma displacing solar elastosis downward.
Nodular BCC
Nodular blue islands with peirpheral palisading, retraction artifact, distinctive fibromyxoid stroma.
Micronodular BCC
Small blue islands with distinctive fibromyxoid stroma surrounding individual islands (but with normal dermis between). Aggressive worm-like growth.
Morpheaform BCC
Thin infiltrating strands of basaloid cells with sclerotic stroma and tadpole-like islands with small horn cysts.
Initially resembles scar but deeply invasive.
Infiltrative BCC
Spiky growth pattern, with fibroblast-rich stroma and common perineural extension. Resembles stroma of trichoepithelioma.
Infundibulocystic BCC
Pink strands and blue buds of tumor. Horn cysts and fibromyxoid stroma. Closely resembles basaloid follicular hamartoma.
Fibroepithelioma of Pinkus
Anastomosing pink epithelial strands in ample fibromyxoid stroma with visible ducts. Blue basaloid buds at the tips and periphery of strands.
Adenoid BCC
Blue islands with an adenoid pattern. Usual peripheral palisading, fibromyxoid stroma, and retraction artifact.
Paget’s disease
Intraepidermal large cells with ample amphophilic cytoplasm. Atypical cells crush the basal layer and may “spit out” into the stratum corneum.
