Chondroid syringoma, also known as a mixed skin tumor, is an infrequent neoplasm that is derived from the sweat glands and forms part of the large group of cutaneous adnexal neoplasms. Originally described by Billroth in 1859, it was not until 1961 that Hirsch and Heldwig first used the term to describe this entity, which is characterized by the presence of an epithelial component within a fibrochondroid stroma.1 This tumor accounts for less than 0.1% of all diagnosed skin tumors.2 Given its low incidence, together with its silent and nonspecific clinical presentation, clinicians often require histological data in order to establish diagnosis. The differential diagnosis should include other adnexal tumors. However, to date there have been no published descriptions of a clinical presentation mimicking basal cell carcinoma, as observed in the case reported here.

A 48-year-old man with no medical history of interest consulted for an asymptomatic, slow-growing nodular lesion (1cm in diameter) with a smooth, pearly surface, located in the upper third of the right nasogenian sulcus (Fig. 1A). Dermoscopy (Fig. 1B) revealed irregular telangiectatic vessels associated with cotton-white structures on an erythematous-white bed. The initial clinical suspicion was nodular basal cell carcinoma. Histology, performed after surgical removal of the tumor, was compatible with chondroid syringoma (Fig. 2).

Figure 1.

A, Red nodule with a smooth surface located in the upper third of the right nasogenian sulcus. B, Dermoscopy. Reddish-white bed with irregular telangiectatic vessels and cotton-white areas.

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Figure 2.

A, Panoramic image showing a dermal tumor with well-defined borders and mild peripheral retraction (hematoxylin-eosin [HE], original magnification ×10). B, Higher magnification image showing cuboidal cells with eosinophilic cytoplasm and without cytological atypia, arranged in strands forming tubular structures (HE, original magnification ×20). C, ocally, the stroma has a chondroid and myxoid appearance (HE, original magnification ×40).

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Chondroid syringoma is a benign tumor of adnexal origin that is more frequent in young men, and is typically located on the head and neck area, in particular on the nose, cheek, and upper lip, although involvement of other regions including the trunk, genital area, and extremities has also been described.3 This tumor is usually solitary and rarely exceeds 2cm in diameter. Malignant transformation is very rare but should be suspected in cases of chondroid syringoma exceeding 3cm and located on the trunk and extremities in young women.4,5 Up to 50% of malignant chondroid syringomas metastasize to the lymph nodes, lungs, or bone.2,6

Chondroid syringoma presents as a well-defined, slow-growing, firm, mobile painless nodule.7 There is no specific, defined dermoscopic pattern that can provide diagnostically useful information.8

The nonspecific clinical and dermoscopic presentation of this neoplasm poses a real diagnostic challenge for dermatologists. The differential diagnosis should include cylindroma, hidradenoma, eccrine poroma, spiradenoma, intradermal nevus, papular mucinosis, and epidermal cyst.7 In our case, the initial clinical suspicion was basal cell carcinoma owing to the atypical presentation of the tumor.

Histology shows a well-defined tumor located in the dermis and/or subcutaneous tissue with epithelial and stromal components. The epithelial component includes glandular-like structures, nests, or cell strands that form ducts and tubules. The stromal component is characterized by a prominent mucinous stroma that eventually becomes chondroid and may contain hyalinized areas and myoepithelial cells.9 Histological characteristics that are considered signs of malignant transformation include asymmetry, cytological atypia, infiltrative margins, satellite tumor nodules, necrosis, and compromise of deep structures.2,10

Complete surgical removal is the treatment of choice, although other therapeutic alternatives such as electrocoagulation, dermabrasion, and vaporization with argon laser or CO2 laser have also been described.2 In cases involving malignant transformation, removal with surgical margins of at least 1cm is recommended, and adjuvant radiotherapy may also be considered.5