'Nuclear grooves' in nodular hidradenoma: frequency and significance of an unrecognized histopatological feature.

Background: Nodular hidradenoma is a distinctive sweat gland neoplasm. In addition to the well-known histological and cytological features, we hereby describe for the first time nuclear grooving as a useful morphological feature to aid in its diagnosis.

Methods: All cases were analyzed for anatomic location, size, age, sex and histology, with attention focused mainly on the nuclear features.