Chondroid syringoma: a case with unusual cytological findings.

Chondroid syringoma is a rare benign skin adnexal tumor, the cytological features of which have been published very rarely in the literature. A mucoid aspirate, abundant chondromyxoid matrix material, and epithelial components were suggested as diagnostic criteria. The reported case is one of chondroid syringoma confirmed by histopathology, the fine needle aspiration cytology of which yielded thin fluid-like material and microscopy revealed epithelial clusters with admixed smaller myoepithelial cells, background cyst macrophages, and only scanty chondromyxoid stromal elements. Including these cytological features of the present case among the diagnostic criteria for cytodiagnosis of chondroid syringomas might increase the chances of a definitive preoperative diagnosis and help in planning the extent of surgery.

What was known?

The rarely described cytological features of chondroid syringoma included a mucoid aspirate, abundant chondromyxoid matrix material and epithelial components.

Introduction

Chondroid syringoma or cutaneous mixed tumors are rare benign skin adnexal tumors accounting for only about 1% of commonly encountered skin tumors.[1] It is now widely accepted that fine needle aspiration cytology (FNAC) is useful in diagnosis of skin adnexal tumors.[2] Cytological features of chondroid syringoma have been published very rarely in the literature.[34] A mucoid aspirate, abundant chondromyxoid matrix material, and epithelial components were suggested as diagnostic criteria. The reported case is one of chondroid syringoma confirmed by histopathology, the FNAC of which yielded thin fluid-like material and microscopy revealed epithelial clusters with admixed smaller myoepithelial cells, background cyst macrophages, and only scanty chondromyxoid stromal elements. These features were subsequently corroborated by histopathological findings.

Case Report

A 31-year-old male patient presented with a solitary 3 cm × 2.5 cm slowly growing, non-tender, cystic left supraorbital swelling [Figure 1a and b]. It was fixed to the skin but freely mobile over underlying structures. The clinical diagnosis was sebaceous or epidermal cyst. FNAC yielded a thin fluid-like aspirate from which Leishman and Pap stained smears were prepared. Microscopic examination revealed moderately cellular smears composed of cohesive clusters of medium-sized epithelial cells with moderate to abundant amount of cytoplasm, peripheral cytoplasmic processes, and bland appearing monomorphic centrally placed or slightly eccentric nucleus with fine chromatin. Few clusters showed vague acinar formations. Smaller hyperchromatic myoepithelial cells were seen intimately admixed with the epithelial cells in most of the clusters [Figure 2]. Fair number of cyst macrophages, a thin proteinaceous material, and only rare chondromyxoid stromal fragments were detected in a predominantly clean background. A cytological diagnosis of benign cystic neoplasm possibly benign skin adnexal tumor was made and excision biopsy suggested.

Figure 1

(a) Left supraorbital swelling. (b) Left supraorbital swelling (closer view)

Figure 2

Epithelial myoepithelial cell clusters in a clean background of thin proteinaceous material and cyst macrophages (inset; seen elsewhere) (Pap; ×100)

Excision biopsy was performed 2 weeks later. Histopathology revealed a chondroid syringoma with extensive cystic changes. Low power showed multiple well-circumscribed cystic spaces lined by tissue having biphasic growth pattern [Figure 3] with epithelial elements in the form of non-branching bilayered tubules as well as solid nests embedded within a predominantly fibrous and focally chondromyxoid stroma. The cystic spaces contained scattered cyst macrophages. Differential diagnoses included eccrine hydrocystoma and syringocystadenoma papilliferum both of which lacked the distinctive chondromyxoid stromal element.

Figure 3

Well-circumscribed cystic spaces lined by tissue having biphasic growth pattern (H and E, ×100). Inset: Bilayered epithelium and characteristic chondromyxoid stroma (H and E, ×400)

Discussion

The term chondroid syringoma, introduced in 1961, may be preferred to the alternative designation-mixed tumor of the skin because of the recognition that the tumor is epithelial with merely secondary changes in the stroma.[5]

The World Health Organization has defined chondroid syringomas as benign adnexal tumors of skin composed of epithelial and stromal elements with a wide spectrum of patterns histologically analogous to mixed tumors of the salivary gland.[6] They most commonly occur as solitary asymptomatic slowly growing nodules on the head and neck of adults, although other sites may be affected.[7] There is a male predilection and most lesions are between 1 and 3 cm in diameter, although examples as large as 10 cm have been reported.[89]

It is generally accepted that there are both apocrine and eccrine variants of mixed tumors. Ultrastructural studies confirm that myoepithelial cells surround the epithelial cells and appear to produce the stromal components of the lesions.[10]

Histologically, two types of chondroid syringomas can be recognized: One with tubular and cystic, partially branching lumina and the other with small tubular lumina. The former type is much more common than the latter and shows marked variation in the size and shape of the tubular lumina; it also shows cystic dilatation and branching. Embedded in an abundant stroma, the tubular lumina are lined by two layers of epithelial cells: A luminal layer of cuboidal cells and a peripheral layer of flattened cells.[1112]

Among the published literature on cytological features of chondroid syringomas, predominance of chondromyxoid elements and presence of only epithelial cell clusters have been more commonly reported.[34] Two reports however confirm the presence of myoepithelial cells.[1314]

The present case had extensive cystic changes which according to the published literature is unusually seen in cytology but consistent with the more common histological type. The cystic change and presence of both epithelial and myoepithelial cells were well represented and easily detectable in the cytological smears.

Conclusion

Including the cytological features of the present case among the diagnostic criteria for cytodiagnosis of chondroid syringomas might increase the chances of a definitive preoperative diagnosis and help in planning the extent of surgery.