Poroid hidradenoma of the scalp

Abstract

Poroid hidradenoma has both features of hidradenoma and poroma. The histological hidradenoma framework consisting of solid and cystic components, and the presence of poroid and cuticular cells resembling a poroid neoplasm. Despite transforming into malignant neoplasm only in < 1% of cases, its histological characteristics may resemble those of malignant neoplasms. Although the risk of malignant transformation is very low, surgical excision is recommended to prevent growth and/or recurrence. To date, very few cases of poroid hidradenoma have been reported in the literature. Herein, we present a case of poroid hidradenoma on the scalp of a 74-year-old woman.

Keywords: Eccrine glands; Poroma; Skin neoplasms.

Fig. 1.

Preoperative photograph showing a 2.0×3.0×0.5 cm round, protruding mass with ulceration and pigmented nodular lesions on the scalp.

Fig. 2.

Second excised specimen measuring about 3.0×4.0×1.0 cm in size.

Fig. 3.

Immediate postoperative photographs. (A) After the first excision. (B) After the second excision.

Fig. 4.

Histologic examination. Solid tumor cell nests composed of small dark poroid cells (white arrow) and larger pale cuticular cells (black arrow) with clear cytoplasm (H&E, ×100).

Fig. 5.

Postoperative photograph. Surgical wound healed uneventfully leaving a scar and little alopecia as observed at the 1-year follow-up visit.