Dermatology Online Journal

Chondroid syringoma: Case report and review of the literature
Raja Sivamani, Akhil Wadhera MD, Errol Craig MD
Dermatology Online Journal 12 (5): 8

University of California, Davis Department of Dermatology

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Abstract

An 84-year-old man presented with an enlarging bluish, painless subcutaneous nodule on the glabella. The lesion had been excised 4 years prior and was diagnosed as chondroid syringoma, but had gradually regrown. The recurrent lesion was treated by surgical re-excision. Histopathological examination was again consistent with chondroid syringoma, and showed the following: 1) a chondroid matrix, 2) tubuloalveolar structures lined by a double epithelium, 3) ductal structures lined by a single epithelium, 4) nests of polygonal cells, and 5) the presence of keratinous cysts. Chondroid syringoma is a rare mixed tumor of the skin that was first described by Hirsch and Helwig. Characteristically, it is composed of a proliferation of epithelial cells set in a myxoid and chondroid matrix. Although chondroid syringomas are predominantly benign, malignant forms have been reported.

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Clinical synopsis

An 84-year-old man presented with a bluish, painless subcutaneous nodule on the glabella that had enlarged and changed color over the past year (Fig. 1). The lesion had been excised 4 years prior and was diagnosed as chondroid syringoma. Recurrent chondroid syringoma was clinically suspected, and the lesion was surgically re-excised.

Histopathological examination revealed a well-circumscribed proliferation of epithelial cells interspersed with foci of myxoid stroma. There were numerous nests of polygonal cells and interconnecting tubuloalveolar structures lined by two layers of cuboidal epithelial cells (Figs. 2-4). The stroma consisted of cells in a bluish chondroid matrix (Figs. 3, 4), areas of fibrosis (Figs. 2, 3, 4), and a lace-like pattern of interconnecting tubuloalveolar epithelial structures (Figs. 3, 4). Ductal structures lined by a single layer of epithelial cells were also apparent (Figs. 2, 3). Keratinous cysts were visible in some of the histological sections (Fig. 4). Cellular pleomorphism or dysplasia was not apparent. The constellation of findings lead to a diagnosis of chondroid syringoma.

Figure 1	Figure 2
Figure 1. Bluish, subcutaneous nodule on the glabella Figure 2. Interconnecting tubuloalveolar structures lined by a double epithelium are visible along with nests of polygonal cells. Hematoxylin and eosin stain; Mag: 400X

Figure 3	Figure 4
Figure 3. Cells are set with a bluish chondroid matrix surrounded by areas of fibrotic stroma. Tubuloalveolar structures lined by double epithelium , rod-like structures, ductal structures lined by a single epithelial layer are visible. Hematoxylin and eosin stain; Mag: 100X Figure 4. The lace-like pattern of the tubuloalveolar structures and the chondroid stroma are apparent in this view. A keratinous cyst is visible. Hematoxylin and eosin; Mag: 40X

Comment

Chondroid syringomas, also known as mixed tumors of the skin, are composed of both epithelial and mesenchymal components. Hirsch and Helwig gave them the appellation chondroid syringoma because of the presence of sweat gland elements set in a cartilaginous stroma [1]. They proposed the following five histological criteria for diagnosis: 1) nests of cuboidal or polygonal cells; 2) intercommunicating tubuloalveolar structures lined with two or more rows of cuboidal cells; 3) ductal structures composed of one or two rows of cuboidal cells; 4) occasional keratinous cysts; 5) a matrix of varying composition. Chondroid syringomas may have all five characteristics or manifest only some [1].

The incidence of chondroid syringoma is low, and has been reported at 0.01-0.098 percent [2]. Lesions are typically located on the head and neck, and are non-ulcerating, slow-growing, subcutaneous, or dermal nodules [1, 2, 3]. However, Sungur et al. reported a benign case where rapid growth, ulceration, and necrosis was evident at the tumor site [4]. Chondroid syringomas affect middle-aged men more than women [2, 3, 5]. Although most are benign, malignant forms have been reported [5, 6, 7, 8, 9, 10, 11]. Unlike its benign counterpart, the malignant form occurs predominantly in females, has no age-related predilection, and is observed more commonly on the extremities [5, 6, 11, 12]. Of the malignant type, 48 percent are reported to have regional lymph node metastasis and 45 percent result in distant metastases [13]. Malignant forms do not arise from a preexisting benign mixed tumor [6, 14] and can display bland features, lacking mitoses or marked nuclear pleomorphism [10]. Excessive amounts of mucoid matrix and poorly differentiated chondroid components serve as important indicators of the tumor's malignancy and metastatic potential [7]. Bates and Baithun discuss mixed tumors that have architectural features suggestive of malignancy but do not conclusively fall into the malignant category. For these they suggested the term atypical mixed tumors [15].

Chondroid syringomas share similarities with pleomorphic adenomas, which are mixed tumors that arise from the salivary glands [16]. In contrast to pleomorphic adenomas, chondroid syringomas are thought to arise from sweat glands. Headington [17] divided chondroid syringomas into apocrine and eccrine variants based on histological differences in the luminal morphology but there remains debate as to their exact origin [18, 19].

The tubuloalveolar components of chondroid syringomas are composed of two layers of cells with different immunophenotypes. The inner layer expresses cytokeratin (CK), epithelial membrane antigen (EMA), and carcinoembryonic antigen (CEA), that is characteristic of cells with an epithelial lineage [5, 20]. The outer layers express vimentin, S-100 protein, neuron-specific enolase (NSE), and in a few cases, glial fibrillary acidic protein (GFAP) [5, 20] that is characteristic of both mesenchymal and epithelial differentiation. Varela-Duran et al. determined that the chondroid area of the tumor shows ultrastructural features identical to myoepithelial cells, a component of the outer layer of cells. They suggest that the chondroid regions are pseudocartilaginous areas that reflect the pluripotentiality of the neoplastic myoepithelial cell [21]. However, subsequent immunohistochemical evaluation of the stroma suggested that myoepithelial cells may not play a major role in the formation of stromal cells [20]. Other studies concluded that the cartilaginous matrix is true cartilage produced by ultrastructurally typical chondrocytes and not pseudocartilage produced by myoepithelial cells [22, 23]. Mills suggests that mixed tumors are monoclonal neoplasms with replicating cells that have the ability to differentiate toward epithelium or mesenchyme, and may account for the histologic variability of mixed tumors of the skin [22].

Optimal treatment of benign chondroid syringomas is surgical excision. Fine needle aspiration cytology has been used for diagnostic purposes and may prove useful to determine pathology before excision, however examination of excised tissue is most reliable in establishing a definitive diagnosis [18, 24]. Because of the lobulated nature of the tumor, it is important to include a margin of normal tissue with the excision to ensure complete removal of the tumor. Otherwise, local recurrence may occur, as was the case in our patient.

Chondroid syringomas are rare, usually benign, tumors occurring predominantly in the head and neck area. They should be included in the clinical differential diagnosis of cutaneous head and neck tumors, especially in middle-aged men. The malignant variant of chondroid syringoma differs from its benign counterpart in that it is more likely to occur on the extremities and is seen more frequently in women.

                 Abbreviations CK: cytokeratin EMA: epithelial membrane antigen CEA: carcinoembryonic antigen NSA: neuron-specific enolase GFAP: glial fibrillary acidic protein

References

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