Panfolliculoma and histopathologic variants: a study of 19 cases.

Panfolliculoma (PF) is an uncommon benign follicular neoplasm exhibiting differentiation toward all components of a hair follicle. Several pathologic manifestations have been described in a limited number of cases. We studied 19 cases of PF to summarize the clinical parameters and to classify this unique neoplasm histopathologically. A study of the largest sample series of PF has been performed here. The lesions affect both genders after age 20. The head is the most common site of PF of all types. On microscopic examination, all cases demonstrated advanced follicular differentiation by showing cell components of infundibulum, isthmus, stem, bulb, and mesenchymal papilla. Based on the findings and various patterns in histopathology, we classified PF into 3 subtypes: nodular, superficial, and cystic. The superficial and cystic variants account for most of the cases in our study. The histopathologic differential diagnosis is also discussed for each subtype.