Apocrine and eccrine hidrocystomas: a clinicopathological study

Introduction: Eccrine and apocrine hidrocystomas are uncommon, benign, cystic proliferations of the sweat glands usually located on the head and neck area. Objectives: To describe the key clinical and histopathological characteristics of a large series of hidrocystomas in Greece to improve diagnostic accuracy, and to perform a historical review of the medical term hidrocystoma. Methods: A case series of 22 hidrocystomas from 20 consecutive patients treated with surgery at University Hospital of Heraklion in Crete, Greece, from January 1, 1998 to January 1, 2020 was performed along with a comprehensive historical literature review of the term hidrocystoma and its corresponding term hydatis from ancient Greek literature to the present. Data were obtained from medical records. All patients had a histopathologically confirmed diagnosis of hidrocystoma. Formalin-fixed paraffin-embedded (FFPE) sections of 22 tumors of the 20 consecutive patients were retrieved from the pathology laboratory archive and stained for SMA, p63, and GCDFP-15 with immunochemistry and periodic acid-Schiff (PAS) histochemical stain. Results: Overall, 22 hidrocystomas (11 apocrine and 11 eccrine hidrocystomas) surgically excised from 20 patients were included in this study. Of the 20 patients, 10 (50%) were male and 10 (50%) were female, with a mean age of 56 +/- 15 years. Hidrocystomas commonly occurred on the eyelids (73%), inner canthus (9%), eyebrow (4.5%), neck (4.5%), nose (4.5%), and ear (4.5%). All apocrine hidrocystomas stained positive for SMA, GCDFP-15, CAM 5.2, PAS, and PAS-D. No recurrence was observed. Conclusions: Here we have presented the clinicopathological characteristics of the largest case series of hidrocystomas in Europe and the Mediterranean region. Only apocrine hidrocystomas stained positive for SMA, GCDFP-15, CAM 5.2, PAS, and PAS-D.