Orthokeratotic Bowen disease: a histopathologic, immunohistochemical and molecular study.

BACKGROUND: Some examples of Bowen disease lack the characteristic broad parakeratosis making their histopathologic diagnosis particularly difficult in small and incomplete biopsies.

MATERIALS AND METHODS: The archives of our dermatopathology laboratory were searched for cases of Bowen disease with >75% orthokeratosis (orthokeratotic Bowen disease) and classic Bowen disease (>25% parakeratosis). Selected specimens were evaluated histopathologically, using immunohistochemical stains (CK10, CK7, Bcl-2, p16 and Ki-67) and by DNA amplification/sequencing for human papilloma virus (HPV) subtypes.

RESULTS: Among 102 consecutive samples 14 cases of orthokeratotic Bowen disease were identified. In comparison with 24 examples of classic Bowen disease, the orthokeratotic examples occurred more frequently in female and younger patients (p = 0.04 and 0.008, respectively) but shared most of the histopathologic features of classic Bowen disease except a preserved granular layer and relative absence of the eyeliner sign (p < 0.0001 and p = 0.042, respectively). Immunohistochemical staining patterns were similar between the two groups. HPV types 11, 16 and 58 were identified from five cases of orthokeratotic Bowen disease.

CONCLUSION: Orthokeratotic Bowen disease is a distinct variant of squamous cell carcinoma in situ associated with HPV infection in less than half of the cases studied.