Chondroid Syringoma of the Leg with Unusual Presentations.

Dear Editor:

Chondroid syringoma (CS) is a rare, benign skin appendageal tumor with a reported incidence of less than 0.01%1. Virchow and Minssen also named the entity mixed tumor of the skin due to its histologic appearance showing both epithelial and mesenchymal origins2. CS characteristically presents as a slow-growing, painless subcutaneous or intradermal tumor and usually affects the head and neck area, trunk, axilla, inguinal area and rarely on eyelids and external ears3.

A 54-year-old female patient presented with a three-year history of a protruding nodule on her right lower leg. She remembered that the nodule had been increasing in size insidiously over the past five years. She did not complain of any subjective symptoms, except aesthetically unpleasant brownish pigmentation. Physical examination showed a 1.5×1.5 cm sized firm, non-tender nodule with a surrounding 3×3 cm sized brownish patch (Fig. 1). We received the patient's consent form about publishing the photograph. There was no localized edema or palpable regional lymphadenopathy. The biopsy demonstrated tubular and gland-like structures embedded in an abundant mucoid stroma (Fig. 2A). The tubular lumina were lined by two layers of luminal cuboidal cells and peripheral flattened cells (Fig. 2B). There was no evidence of necrosis or atypia. The epidermis showed mild hyperkeratosis and increased basal pigmentation. The diagnosis of CS was confirmed, and the patient underwent complete excision.

Fig. 1

A protruding solid nodule with a peripheral brownish patch on the lower leg.

Fig. 2

(A) Low power view shows nodular dermal mass with overlying epidermis of increased basal pigmentation (H&E, ×40). (B) Low power view shows abundant basophilic stroma (H&E, ×100). (C) High power histologic feature shows a nodular dermal tumor composed of branching tubular epithelial elements embedded in a myxoid stroma (H&E, ×200). No atypical cells are observed.

CS is usually not recognized by physicians due to its relative infrequency and silent clinical course. Since CS is clinically indistinctive, the diagnosis relies largely on histologic examination. Histopathologically, CS demonstrates nests of cuboidal or polygonal cells and ducts surrounded by chondromyxoid stroma. It typically shows inter-communicating tubuloalveolar structures composed of one or two rows of cuboidal cells.

CS usually presents in the head and neck area, except for rare cases involving the trunk, back, or extremities3. Axillar, cerebral, scrotal, or vulvar cases have also been reported as very rare localizations1. The present case was located in the lower leg. To the best of our knowledge, this is only the second of two cases on the lower leg, the first of which was reported by Sulochana et al.4.

Since our case showed peripheral brownish pigmentation around the nodule, we worried about possible invasion by malignant transformation5, which was, however, not found in the pathology. Considering that the patient persistently squeezed and irritated the nodule to remove it by herself, the dark pigmentation may be due to postinflammatory hyperpigmentation. Because the lesion was located on an extremity and occurred in a female patient, we recommended including a margin of normal tissue with the complete removal of the tumor.

We report this case because CS is an uncommon, confusing adnexal tumor. Especially in this case, the nodule showed atypical location on the leg and hyperpigmentation, which misled us about clinical impression. By pathologically confirming tubular epithelium and basophilic stroma, CS was finally diagnosed. Due to the potential risk of malignant transformation, surgical excision and close follow-up are recommended.