The clinicopathological spectrum of trichoepitheliomas: a retrospective descriptive study

Differentiation of Basal Cell Carcinoma and Trichoepithelioma: An Immunohistochemical Study

ABSTRACT

Basal cell carcinoma (BCC) is the most common malignancy of the skin. It is an epithelial neoplasm with origin in the precursor cells of the interfollicular epidermis. Even though it has low metastatic potential, delay in management may lead to local destruction and morbidity. In contrast, trichoepithelioma (TE) is a benign tumor originating from the outer root sheath of the hair follicle. Similar to BCC, TE tends to affect the head and neck region. Both neoplasms may exhibit clinical and histopathological similarities, making them prone to misdiagnosis. Multiple immunomarkers have been used to distinguish among these entities, but so far, no single agent or combination of agents appear to be neither sensitive nor specific enough to differentiate between them. This study was divided into 2 parts. First, 17 cases of BCC and 14 cases of TE were stained with androgen receptor and bcl-2. Then, 27 cases of borderline/equivocal of BCC and 13 cases of borderline/equivocal TE were stained with the same protocol. Sensitivity and specificity were calculated for each individual immunomarker and for the combination of them. Androgen receptor positivity was 100% specific for BCC and borderline/equivocal BCC, whereas bcl-2 diffuse staining pattern demonstrated a sensitivity of 82.4% for BCC and 88.9% borderline/equivocal BCC. When both immunomarkers were combined, the sensitivity for BCC decreased (70.6%) but the specificity remained high (100%). Similarly, the sensitivity for borderline/equivocal BCC was 55.6%, whereas the specificity was 100%. Although moderately sensitive, combining both immunomarkers showed an excellent specificity to discriminate between BCC and TE.

A large family with CYLD cutaneous syndrome: medical genetics at the community level

Germline mutations in the cylindromatosis gene (CYLD) are associated with a rare autosomal dominant disease known as CYLD cutaneous syndrome (CCS). Patients present multiple neoplasms originating from skin appendages. Here, we investigated the main clinical and molecular features of a large family with CCS having lived in a small Brazilian town for 6 generations, making its prevalence significantly high. We observed a predominance of the disease among males and a wide phenotypic variation. A high frequency of basal cell carcinomas among affected people was found. The mutation c.2806C>T, p.Arg936* in the CYLD gene was detected in all patients. In this work, a geographical cluster of CCS was found, which raised some community genetics issues related not only to the high prevalence of a rare disease in a limited area but also to the strong social stigma associated with the disease.

Histologic Mimics of Basal Cell Carcinoma

CONTEXT

- Basal cell carcinoma (BCC) is the most common human malignant neoplasm and is a frequently encountered diagnosis in dermatopathology. Although BCC may be locally destructive, it rarely metastasizes. Many diagnostic entities display morphologic and immunophenotypic overlap with BCC, including nonneoplastic processes, such as follicular induction over dermatofibroma; benign follicular tumors, such as trichoblastoma, trichoepithelioma, or basaloid follicular hamartoma; and malignant tumors, such as sebaceous carcinoma or Merkel cell carcinoma. Thus, misdiagnosis has significant potential to result in overtreatment or undertreatment.

OBJECTIVE

- To review key features distinguishing BCC from histologic mimics, including current evidence regarding immunohistochemical markers useful for that distinction.

DATA SOURCES

- Review of pertinent literature on BCC immunohistochemistry and differential diagnosis.

CONCLUSIONS

- In most cases, BCC can be reliably diagnosed by histopathologic features. Immunohistochemistry may provide useful ancillary data in certain cases. Awareness of potential mimics is critical to avoid misdiagnosis and resulting inappropriate management.