Practical immunohistochemistry of epithelial skin tumor

Abstract

Skin tumors are tumors arising from keratinocyte and from adnexal structures. Immunohistochemistry is very helpful in diagnosis of difficult cases in epithelial skin neoplasms, especially basal cell carcinoma (BCC) which is positive for BerEP4, a keratin marker, and mostly negative for epithelial membrane antigen (EMA). Squamous cell carcinoma cells are positive for EMA and cytokeratin, which are of higher molecular weight than those found in BCC. In contrast to BCC, trichoblastoma and trichoepithelioma are negative for androgen receptors. Of the malignant dermal spindle cell lesions, spindle cell squamous carcinoma is positive to 34 betaE12, desmoplasmic melanoma is positive to S100, and leiomyosarcoma is positive to desmin. Of the malignant pagetoid cells, Paget's disease is positive to CK7 and cam5.2, whereas the pagetoid variant of Bowen's disease is positive to CK 5/6. Melanoma in-situ is positive to both S100 and melan-A. Immunohistochemistry is an extremely valuable adjunct to standard morphologic diagnosis in diagnostic pathology. Diagnosis of epithelial tumor depends largely on morphological features but, in rare cases, immunohistochemical stains are needed for definitive diagnosis.

Basal cell carcinoma vs basaloid squamous cell carcinoma of the skin: an immunohistochemical reappraisal

“…In this series, all cases of MBCC exhibited immunoreactivity with Ber-EP4, as shown previously by others (2,3,21,32). In contrast, only 16% of BSCCs showed positive staining with that marker.…”

Histological and immunohistochemical practical studies of canine cutaneous tumors

“…A precise morphological identification of the origin and type of tumor cells makes it possible to identify and treat this disease in its early stages (3). The diagnosis of cutaneous tumors depends on histological features; however, immunohistochemistry is a very important auxiliary tool for a definitive diagnosis of the tumor (1,12). It is also the basic most effective technique for determining the origin of a tissue or the differentiation of neoplastic cells (12).…”

Simple approach to histological diagnosis of common skin adnexal tumors

“…EMA immunoperoxidase staining remains the best supplemental test for confirmation of sebaceous differentiation. 7 Sebaceous carcinoma differs from sebaceous adenoma and sebaceoma in its asymmetry, poor circumscription, infiltrative growth pattern, and solid sheets and shows atypia and high mitotic activity.…”

“…10 The basaloid cells of pilomatrixoma and pilomatrix carcinoma express B-catenin. 7 No epidermal connection + basaloid tumor + cuticle (small ducts) formation = dermal duct tumor.…”

“…7 Cutaneous lymphadenoma is a rare variant of trichoblastoma that is composed of multiple rounded lobules of basaloid cells with peripheral palisading and infiltrate of small mature lymphocytes. 1 No epidermal connection + basaloid tumor + two cell types + intermingled lymphocytes = spiradenoma and cylindroma Spiradenoma is a benign dermal neoplasm that can show either eccrine or apocrine differentiation.…”