Bcl-2 overexpression in basaloid proliferations overlying dermatofibromas and basal cell carcinomas

Skin adnexal neoplasms--part 1: an approach to tumours of the pilosebaceous unit

Skin adnexal neoplasms comprise a wide spectrum of benign and malignant tumours that exhibit morphological differentiation towards one or more types of adnexal structures found in normal skin. Most adnexal neoplasms are relatively uncommonly encountered in routine practice, and pathologists can recognise a limited number of frequently encountered tumours. In this review, the first of two, the normal histology of the skin adnexal structures is reviewed, and the histological features of selected but important benign and malignant tumours and tumour-like lesions of pilosebaceous origin discussed, with emphasis on the diagnostic approach and pitfalls in histological diagnosis.

[Basal cell carcinoma overlying a dermatofibroma]

The epidermis over a dermatofibroma may show changes that range from simple hyperplasia to the proliferation of basaloid cells, which can become morphologically indistinguishable from basal cell carcinoma. The existence of a true basal cell carcinoma overlying a dermatofibroma is infrequent. These basaloid proliferations have usually been considered to be the result of the inductive effect of the fibrohistiocytic proliferation of the dermatofibroma on the epithelial cells of the hair follicle; therefore, it would be a reactive phenomenon and not truly neoplastic. We describe a case of dermatofibroma that presented with a basaloid proliferation identical in appearance to a basal cell carcinoma on the overlying epidermis.

Anti-cytokeratin 20 staining of Merkel cells helps differentiate basaloid proliferations overlying dermatofibromas from basal cell carcinoma

BACKGROUND

Basaloid epidermal proliferations (BEP), morphologically resembling basal cell carcinoma (BCC), have been described overlying dermatofibromas. Distinguishing the two is important because of non-aggressiveness of BEP and local aggressiveness of BCC. The aim of this study is to determine whether CK20 antibody staining for Merkel cells can be used as an adjunct method to differentiate BEP from BCC.

METHODS

Ten cases of BEP overlying dermatofibromas were selected. Ten cases of BCC were used as control. The two groups were stained with CK20 antibody. Numerical density of CK20 stained Merkel cells in peri-lesional epidermis, BEP and BCC was determined by examining 300 cells at 400X in two separate areas by three independent pathologists. To determine statistical significance, the results were compared using t-test method.

RESULTS

Density of Merkel cells in peri-lesional epidermis was 0.2-0.3%. No merkel cells were detected in the BCC. BEP overlying dermatofibromas showed an obvious increase in CK 20 stained Merkel cells. The difference was statistically significant (P < 0.02) CONCLUSIONS: We report a significant increase in CK20 stained Merkel cells in BEP overlying dermatofibromas as compared to BCC. CK20 antibody staining for Merkel cells can be used as an adjunct method to differentiate BEP overlying dermatofibromas from BCC. Mahmoodi M, Asad H, Salim S, Kantor G, Minimo C. Anti-CK20 staining of Merkel cells helps differentiate basaloid proliferations overlying dermatofibromas from basal cell carcinoma.

Carcinomas basocelulares: estudo clínico e anatomopatológico de 704 tumores

FUNDAMENTOS: Este é um estudo retrospectivo e anatomopatológico de 704 carcinomas basocelulares de 623 pacientes, diagnosticados no período de 1991 a 1996, no setor de Dermatopatologia da Clínica Dermatológica do Hospital das Clínicas da UFPE e em um laboratório privado de dermatopatologia da cidade do Recife. OBJETIVOS: Caracterizar aspectos clínicos e anatomopatológicos dos carcinomas basocelulares diagnosticados nos dois serviços da região de Pernambuco. MÉTODOS: Para o estudo clínico, os dados foram retirados dos prontuários e para o estudo anatomopatológico, macro e microscópicos, foram feitas revisão dos preparados histológicos. Para o crescimento vertical empregaram-se métodos baseados nas técnicas histoprognósticas de Clark e Breslow, aplicadas ao melanoma maligno. RESULTADOS: Clínicos: a maior incidência foi no sexo feminino (55,7%), faixa etária de 55 a 72 anos, tempo de evolução com variabilidade elevadíssima, desde um mês a 40 anos, e a cabeça foi a região topográfica mais freqüente (73,8%), principalmente nasal (21,1%) e zigomática (18,5%). A forma nodular pigmentada (47,4%) foi a mais encontrada e o tamanho das lesões independeu do tempo evolutivo. Histologicamente os padrões considerados baseados apenas nos arranjos parenquimais, foram os adenóide, compacto, fibroepitelial de Pinkus plexiforme, pseudocístico, reticulado, superficial e tricoepitelial, predominando o adenóide (28,3%). A média de crescimento foi em 2/3 da derme reticular (32,4%), e os tumores que mais se aprofundaram mostraram fibroplasia intensa. Houve concomitância de vários tipos celulares em um mesmo tumor e o pigmento melânico esteve mais presente nos tricoepitelioides. CONCLUSÃO: A fundamental importância da caracterização clínica e anatomopatológica dos carcinomas basocelulares destes serviços, sem diferenças muito significativas para os grupos e atenção para definições comportamentais e proposições ao relatório histopatológico.

Proliferation and differentiation of the keratinocytes in hyperplastic epidermis overlying dermatofibroma: immunohistochemical characterization

Epidermal changes overlying dermatofibromas (DFs) have been described as ranging from psoriasiform simple hyperplasia to basaloid hyperplasia sometimes morphologically indistinguishable from superficial basal cell carcinoma (BCC). To characterize epidermal hyperplasia overlying DFs and to determine its association with the disease process, we examined 30 cases of DF showing hyperplastic epidermis. We used nine immunohistochemical markers associated with keratinocyte proliferation or differentiation. In DFs, the dermal metallothionein (MT) expression and immunophenotypic changes with regard to epidermal differentiation varied depending on the stage of lesional evolution of the DFs. Immunostaining for epidermal growth factor receptor (EGFR), MT, and keratin 6 (K6) increased in simple hyperplastic epidermis (SHE) overlying DFs (n = 11), whereas it gradually diminished in basaloid hyperplastic epidermis (BHE) overlying DFs (n = 19). In SHE, there was a significant increase in K14 expression. Among 19 BHE cases, 12 showed premature expression of involucrin and delayed appearance of K1 along with aberrant expression of K14. Conversely, the remaining 7 BHE cases showed a pattern of involucrin and K1 similar to that of normal skin coinciding with decreased or absent dermal MT expression. Loricrin and filaggrin expression in all DFs was the same as that of normal skin. Based on the sparse positivity of Ki-67 in the hyperplastic epidermis overlying DFs, we found that the biologic ability of BHE and SHE was not apparent in the hyperproliferative state observed in psoriasis and BCC. These results suggest that the dermal fibrohistiocytic process may trigger the induction of SHE overlying DFs by an unknown mechanism and then mediate both the abnormal keratinocyte differentiation and the transformation of SHE to BHE through the evolution of the dermal lesions.

BAX protein is not expressed by basal cell carcinomas

BAX and related proteins encoded by the BCL2 gene family are involved in the regulation of apoptosis. BAX is an apoptosis-promoting protein. The slow growth of basal cell carcinoma (BCC) has so far been explained by a high apoptotic activity. We investigated immunohistochemically 27 BCCs for expression of the apoptosis-promoting BAX protein. BCC did not express detectable amounts of BAX immunohistochemically. The results indicate that apoptosis in BCC does not involve BAX protein. We propose that the apoptotic pathway in BCC is regulated by either less common members of the BCL2 gene family or bypasses the regulation of the BCL2 gene family.