Pemphigus vulgaris of the vagina--its cytomorphologic features on liquid-based cytology and pitfalls: case report and cytological differential diagnosis.

Pemphigus vulgaris is an autoimmune bullous disease that involves skin and mucous membrane. Although the female genital tract is rarely affected, its cytomorphologic features on a conventional cervicovaginal smear have been notoriously described with a possibility of being misdiagnosed as neoplastic lesions. Its cytological mimicry for squamous cell carcinoma has been described as having serious misdiagnostic potential, particularly if appropriate clinical information is not provided. We report a case of pemphigus vulgaris involving the vagina diagnosed on a liquid-based cervicovaginal smear Thin Prep(R) (TP). The smear was initially reported as squamous cell carcinoma. However, re-evaluation of the TP smear raised the suspicion of pemphigus, which was supported subsequently by clinical information and tissue biopsy confirmation. We described the cytologic features of pemphigus vulgaris on a TP smear and compared them with those of neoplastic conditions. Pemphigus cells on a TP smear exhibit similar cytomorphologic features to those on a conventional smear. Recognizing euchromatin pattern and smooth nuclear contours which may be better appreciated on a TP can prevent overdiagnosis.