To the Editor:
Chondroid syringoma is a rare benign mixed tumor that originates from the sweat glands, typically presenting with both epithelial and mesenchymal components.1 It differs from pleomorphic adenoma, which arises from salivary glands. The surgical approach for complete excision is different for the 2 tumors; therefore, definitive diagnosis is important. For chondroid syringoma, total excision is recommended,2 while for pleomorphic adenoma, extracapsular dissection or superficial parotidectomy is commonly indicated. We report a case of a preauricular nodule at presentation and highlight the importance of differentiating a chondroid syringoma from a pleomorphic adenoma. This case is unique because of the anatomic location of the nodule, making diagnosis difficult because the tumor was abutting the parotid gland and a biopsy included normal salivary gland cells.
A 19-year-old man with a history of moderate acne on the shoulders, back, and face presented with a rapidly growing, painless nodule on right preauricular region of 6 months’ duration. The nodule was originally thought to be acne related and monitored, as the patient was asymptomatic. On examination the patient was found to have a firm, fixed, nontender, subcutaneous nodule overlying the right temporomandibular joint just anterior to the right tragus (Figure 1). Laboratory results were unremarkable. Computed tomography showed a subcutaneous nonaggressive-appearing soft-tissue mass measuring 16×17×12 mm just anterior and inferior to the external auditory canal cartilaginous segment with no bony abnormalities. The patient was initially treated with incomplete excision of the area for a presumed sebaceous cyst; 2 months later, an abnormal biopsy prompted a complete excisional biopsy.
Figure 1. A preauricular nodule overlying the temporomandibular joint.
Histologically, the initial incomplete excision biopsy revealed myxoid and chondroid tissue with glandular elements and adjacent lymph node with strong positivity for S-100 protein and moderate positivity for glial fibrillary acid protein, consistent with chondroid syringoma (Figure 2). Histological findings on second excision biopsy performed 2 months later showed tumor cells surrounded by normal salivary gland cells; therefore, it was difficult to define the origin of this tumor. Subsequent magnetic resonance imaging showed no evidence of the tumor and normal parotid gland borders.
Figure 2. Histology showed myxoid and chondroid elements (H&E, original magnification ×10).