A case of an unusual eccrine poroma on the left forearm area

Abstract

A 40-year-old woman presented with an asymptomatic red to brown colored walnut-sized, dome shaped, hemorrhagic, crusted nodule on the left forearm. There was no previous history of trauma to the area. The first impression of this case was a vascular tumor or malignant lesion due to the large size and bleeding tendency. However, the final diagnosis, according to histologic and immunostaining methods, was a benign eccrine poroma that occurred on the left forearm, which is an unusual area for such a lesion. The tumor was excised and no recurrence was noted when she was examined 24 months later.

Keywords: Eccrine poroma; Forearm.

Fig. 1

(A) A solitary 2.0×2.0 cm sized red to brown-colored mass on the left forearm. (B) The mass seemed to be pedunculated and it had a rough surface that showed hemorrhagic crusts and erosions.

Fig. 2

(A) A single pedunculated large tumor mass and well-circumscribed tumor nests within the epidermis and these nests were located at the periphery of the mass (H&E, 1:1 direct view). (B) This scanning view showed the interconnected epithelial downward growth with multiple foci of attachment to the epidermis (H&E, ×40). (C) The tumor cells were small and they showed a uniform cuboidal appearance with basophilic, round nuclei and the tumor cells were connected by intercellular bridges (H&E, ×400). (D) There were conspicuous intracytoplasmic lumina (H&E, ×100). The tumor cells showed slightly increased mitotic figures (inset). (E) The tumor cells contained periodic acid-Schiff (PAS)-positive materials (H&E, ×200) and d-PAS positive materials (inset).

Fig. 3

(A) The ductal lining stained positive for carcinoembryogenic antigen (H&E, ×100). The tumor cells stained positive for epithelial membrane antigen (B: H&E, ×100), negative for S-100 (C: H&E, ×100), and less than 10% of the tumor cells were positive for Ki-67 (D: H&E, ×200) and p53 (E: H&E, ×200).