Fibromatosis
4-6% of Caucasian adults > 50 years of age • Deep fibromatosis 2.40-4.43 new cases per 100,000 persons/year • Recurrences common for both superficial and deep fibromatoses, but deaths only from deep…
Verrucous Carcinoma (and Variants)
Other locations are less frequent • Usually solitary Multicentric tumors can occur • Some cases may be associated with viral warts (plantar lesions) • Verrucous carcinoma (VC) may arise in setting of longstanding…
Epithelioid Hemangioendothelioma
Multicentricity at presentation likely represents locoregional metastases • Treatment: Wide surgical excision with negative margins • Indolent clinical course in majority of cases • Metastases in 20-30% • Overall mortality rate of 10-20% High-risk…
Trichoepithelioma
Superficial folliculocystic structures and calcifications Deeper infiltrative-appearing cords and small islands in densely fibrotic stroma Top Differential Diagnoses • Basal cell carcinoma • Microcystic adnexal carcinoma • Trichoblastoma • Trichoadenoma • Sebaceoma Clinical Photograph of…
Cylindroma
Can have areas indistinguishable from cylindroma Usually encapsulated Tumor stroma has prominent vasculature • Malignant cylindroma/cylindrocarcinoma • Basal cell carcinoma Peripheral palisading with tumor-stroma retraction • Trichoblastoma Tumor lobule surrounded by fibroblastic stroma;…
Rhabdomyoma
Adult, fetal, and genital types Etiology/Pathogenesis • No association with tuberous sclerosis (unlike cardiac type) • Some fetal rhabdomyomas associated with nevoid basal cell carcinoma syndrome (Gorlin syndrome) Clinical Issues • Fetal type:…
Staging for Specimens of Malignant Melanoma of Skin
pT1a: Melanoma ≤ 1.0 mm, no ulceration, no mitoses pT1b: Melanoma ≤ 1.0 mm, with ulceration &/or mitoses (≥ 1/mm²) • pT2: Melanoma > 1.0 – 2.0 mm in thickness pT2a:…
Primary Neuroendocrine (Merkel Cell) Carcinoma
Especially lung, which are TTF-1(+), CK20(-) • Small cell melanoma • Lymphoma Clinical Photograph of MCCClinical photograph of Merkel cell carcinoma (MCC) shows a well-circumscribed, erythematous dermal nodule. (Courtesy J. Wu, MD.)…
Deep Penetrating Nevi
DPN Showing Wedge-Shaped InfiltrateThis is a subtle case of deep penetrating nevus (DPN) on low-power examination. There are, however, dermally located subtle nests and fascicles of melanocytes . There is…
Aggressive Epidermotropic CD8(+) Cytotoxic T-Cell Lymphoma
Often disseminated tumors, nodules, and papules Rapid spread to lungs, testes, brain, and oral cavity Often treated with multiagent chemotherapy • Often spares lymph nodes • Rare compared to other cutaneous T-cell…
