Solitary Eccrine Syringofibroadenoma of the Dorsum of Hand

Sir,

A 50-year-old woman presented with a papule on her left hand dorsum for 3 months. The lesion was asymptomatic but occasionally bled because of picking. The woman was healthy and denied previous trauma, relevant family history, or any systemic disease like diabetes. Physical examination revealed a flesh-colored papule of 0.4 cm in diameter on her left hand dorsum and mild erosion on the surface of the papule [Figure 1]. The examination of hair, mucosae, and nails was normal. We resected the lesion. Histopathological examination revealed thin, interconnected cell cords extending from multiple sites of the epidermis to the middle layer of the dermis, surrounded by fibrovascular stroma. The cell cords were composed of small squamous cells, some of which formed small ductal structures. A complete eosinophilic membrane was wrapped around the edge of the lumen [Figure 2]. The immunohistochemical stainings for endothelial membrane antigen (EMA) and periodic acid-Schiff (PAS) were both positive [Figure 3]. Bilayer structure of the glandular arrangement, positive of PAS and EMA, supported the origin of eccrine sweat glands. Thus, we diagnosed eccrine syringofibroadenoma (ESFA). The patient remained free of recurrence at 6-month follow-up.

Figure 1.

A flesh-colored papule approximately 0.4 cm in diameter on the dorsum of left hand

Figure 2.

The thin epithelial intertwined cords derived from the epidermis and surrounded by fibrovascular stroma (H and E, [a] ×40, [b] ×100)

Figure 3.

The immunohistochemical staining of (a) endothelial membrane antigen and (b) periodic acid-Schiff were positive (×200)

ESFA is a rare benign tumor of eccrine sweat gland, which can be divided into five subtypes: (1) solitary, (2) multiple, connected with hidrotic ectodermal dysplasia, (3) multiple, without connected cutaneous features, (4) unilateral linear, and (5) reactive ESFA.[1] All clinical subtypes have similar typical histopathological features as anastomosing cords and strands of uniform epithelial cells surrounded by fibrovascular stroma.

Clinically, pyogenic granuloma and verruca vulgaris should be taken into consideration for differential diagnosis. The former usually has a history of trauma, which is characterized by red or dark-red papules and nodules, and the latter has a rough or verrucous surface. Both of them can be distinguished easily according to the histopathological examination.

The histopathological differential diagnosis may include acrosyringeal nevus, fibroepithelial tumor of Pinkus, eccrine poroma, and syringofibroadenocarcinoma.[2] Plasma cell infiltrates, and strong PAS positivity is characteristic of acrosyringeal nevi. The fibroepithelial tumor of Pinkus shows local changes (typical of basal cell carcinoma) with peripheral palisade and suturing artifacts and a loose fibrous matrix. Eccrine poromas show more uniform proliferation of small epithelial cells with vertical thick strands stretching into the dermis. Syringofibroadenocarcinomas display a shift where malignant phenotypic cytogenetic abnormalities can be seen.

ESFA is rare, with only about 50 cases reported.[1] ESFA has been reported in the heel, dorsum of foot, leg, finger, and perianal region. To the best of our knowledge, only one case has been reported from China, and that case mimicked verruca vulgaris on the extremities.[3] Our patient presented a minute papule on the dorsum of hand. Compared with other patients, the present patient had a smaller lesion and shorter clinical course.

ESFA is a benign tumor. However, malignant transformation into eccrine porocarcinoma, syringofibroadenocarcinoma, or a correlation with squamous cell carcinoma have been reported.[4,5] Hence, the recommended treatment of ESFA is surgical excision to prevent possible malignant transformation. Laser treatment and cryotherapy are not recommended before a definite diagnosis.

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