Unusual sites for poromas are not very unusual: a survey of 101 cases

Poromas are benign adnexal tumours generally believed to be of eccrine origin, which usually develop on palmoplantar sites. However, it is thought that a percentage of poromas develop on non-palmoplantar or 'unusual' sites.

To review cases of poromas with reference to their clinicoepidemiological characteristics, paying particular attention to the those located on sites other than the palms and soles.

All histologically confirmed poromas seen at our department between 1994 to 2012 were reviewed. The clinicoepidemiological data recorded included age at diagnosis, gender, location, size, colour, and preoperative and pathological diagnoses.

In total, 101 poromas were reviewed, corresponding to 0.0058% of all the epithelial skin tumours biopsied in our department. The mean age was 65.05 years (range 30-100 years), and the male to female ratio was 1.52. All the lesions were solitary and asymptomatic, with no sign of bleeding. The most common presentation was a red or reddish lesion, particularly at palmoplantar sites, where 33 (32.7%) of the 101 poromas were located, Poromas found at other affected sites were more usually skin-coloured, and these lesions included 7 neoplasms located in the armpits and 18 on the head and neck. The correct preoperative diagnosis was made in 12 cases of 33 detected poromas (36%), all of which were localized to the palmoplantar surfaces.

Based on our experience, we consider that there are no 'unusual' sites for poromas, and palmoplantar poromas were in fact in the minority. Furthermore, some localizations suggest derivation of these palmoplantar poromas from the folliculosebaceous apocrine unit.