Unusual sites with variable presentation of de novo syringocystadenoma papilliferum: A case series

Syringocystadenoma papilliferum (SCAP) is an uncommon, benign adnexal neoplasm that occurs de novo or in an organoid nevus. It usually presents as a skin-coloured to pink, solitary, smooth, hairless plaque, verruca or nodule frequently on the scalp and forehead. SCAP may be present at unusual sites including the arm, forearm, trunk and chest. Diagnosing SCAP arising on uncommon sites is difficult owing to its varied presentation. Mostly, they are wrongly diagnosed clinically and found to be SCAP only on histopathology. We present this study of cases of SCAP with unusual location and varied presentations, which were clinically misdiagnosed. The five cases included in this study were patients attending the dermatology outpatient department in a tertiary care centre in North India. The clinical presentation and the involved sites were noted by the dermatologist, and a clinical diagnosis was made. Biopsy of the lesions was sent for histopathological examination. There are five patients in the series - four are male and one female, with age ranging from 28 to 48 years. Locations included the forearm, arm, anterior chest wall and lateral abdominal wall. The lesions clinically appeared as warty papule or nodules and one lesion appeared within a plaque, with the average duration being 5.3 years. In all five patients, the lesions were clinically suspected to be either tuberculosis verruca cutis or nodular basal cell carcinoma or dermatofibroma sarcoma protuberans (DFSP) or verruca or fibroma or pyogenic granuloma. A confirmatory diagnosis of SCAP was made for all the patients on histopathology. We are presenting five cases which were misdiagnosed clinically due to the unusual location and varied presentation to emphasise the importance of histopathology in diagnosing SCAP arising de novo, which was clinically misdiagnosed. Also, we present this case series to alert the clinicians about the likelihood of SCAP on unusual locations with varied clinical presentation.