A Case of a Malignant Cutaneous Mixed Tumor (Chondroid Syringoma) of the Scapula Treated With Staged Margin-Controlled Excision

Abstract

Cutaneous mixed tumor (chondroid syringoma) is the cutaneous counterpart of pleomorphic adenoma of salivary glands, comprised of both epithelial and mesenchymal components. Malignant transformation is exceptionally rare, with only a few cases reported. We report a case of a malignant cutaneous mixed tumor in an 86-year-old white man who presented with a pink indurated plaque on his left scapula. He had a history of nonmelanoma skin cancers, a stage IB malignant melanoma of a lower extremity and Gleason 4 + 3 prostate cancer treated with brachytherapy, external beam irradiation, and bicalutamide. A shave biopsy was performed and histologic examination revealed infiltrative single-unit atypical cells and small ducts in a superficially transected sclerotic dermis suggestive of a poorly differentiated adenocarcinoma. No epidermal connection was identified. Immunohistochemical studies revealed that the tumor was positive for CK7, CAM5.2, and mCEA and negative for CK20, epithelial membrane antigen, P63, prostate-specific antigen, prostatic specific acid phosphatase, and alpha-methylacyl-coenzyme A racemase. A metastasis of the breast or upper digestive tract was favored, although a primary eccrine carcinoma was also considered. Imaging was performed and no other masses were identified. A slow Mohs excision was performed with negative margins. Microscopic examination revealed a biphasic neoplasm comprised of infiltrative epithelial strands and tubules consistent with an eccrine carcinoma in a hyalinized and chondromyxoid stroma within the dermis, arising from a well-circumscribed chondroid syringoma located in the deep dermis and subcutis. Areas of clear cell change, intracytoplasmic vacuolization, and mucin pools were noted. Multiple foci of perineural invasion were identified. Additional immunohistochemical studies revealed that the tumor was positive for S100 and negative for CK5/6, calponin, glial fibrillary acidic protein, GATA3, GCDFP-15, and mammoglobin. Based on the morphologic features and immunoprofile, this was diagnosed as a malignant cutaneous mixed tumor. This case highlights the importance of obtaining adequate tissue for histologic evaluation, as they can be confused with other skin neoplasms because of their clinically ambiguous presentations. Although rare, an accurate diagnosis is important given that long-term follow-up is recommended because of the risk of local recurrence and both lymph node and distant metastases.

Malignant Chondroid Syringoma: A Report of Two Cases with a Sarcomatous Mesenchymal Component

“…Usual presentation is in the fourth decade of life [8, 13]. The age range, however, is wide with the youngest recorded patient aged 14 years and the oldest 86 years at the time of diagnosis [3, 13]. Tumour size is variable, with some documented neoplasms attaining a diameter of up to 8 cm, similar to case 2 in the present report [9].…”

“…MCS is a very rare malignant cutaneous adnexal neoplasm and is said to account for only 0.01% of all primary skin tumours [1]. The majority of cases recorded in the English medical literature have been in the form of single case reports [4, 7, 10, 11, 12, 13, 14]. Synonymous terms include malignant mixed tumour of skin [14], cutaneous malignant mixed tumour [15], metastasising chondroid syringoma [16] and aggressive chondroid syringoma [17].…”

“…The tumour typically occurs as a rapidly enlarging nodule on the extremities either proximally or distally and on either the upper or lower limb [3, 7, 8, 11, 18]. Other reported sites include the sacral region [5, 11] and the head and neck area, including the scalp, face and external acoustic meatus [3, 4, 5, 10, 11, 13]. The tumour appears to be more prevalent among females.…”

“…The tumour appears to be more prevalent among females. Usual presentation is in the fourth decade of life [8, 13]. The age range, however, is wide with the youngest recorded patient aged 14 years and the oldest 86 years at the time of diagnosis [3, 13].…”

A Rare Forehead Mass: The Chondroid Syringoma

“…Rapid growth or ulceration should prompt concern for a malignancy, which is very rare in these tumors. Pathology typically reveals a well-circumscribed nodule seen within the deep dermis or subcutis [3]. The term Chondroid Syringoma by Hirsch and Helwig was in place of pleomorphic adenoma of the skin, as the tumor is epithelial in nature, with associated secondary changes in the stroma [1].…”