Malignant chondroid syringoma: A systematic review

Malignant Chondroid Syringomas (MCS) are very rare malignant tumours arising from cutaneous sweat glands, with only 51 reported cases in the literature. These tumours can metastasize and cause death if not treated adequately. While there are histological criteria to diagnose MCS tumours, there are no established criterion to determine which tumours are more or less likely to metastasize. A systematic review was performed to establish if any features of the primary MCS tumour are associated with risk of metastasis or patient mortality, as well as the efficacy of common treatment options. The literature search was performed using the Ovid Medline and Web of Science databases from inception through March 2020. This yielded 47 case reports corresponding to 51 unique patients. Statistical analysis of the collected data revealed none of the commonly accepted malignant histopathologic findings (including nuclear atypia and/or pleomorphism, mitotic figures, an infiltrative growth pattern, presence of satellite nodules, necrosis, and vascular and/or perineural invasion) of the primary tumour to be significantly more associated with metastatic risk or death. However, gross characteristics of the tumour, including size (greater than 5 cm) and truncal location of the primary lesion, were found to be associated with a higher risk of metastasis. The most effective treatment modality was wide local excision. Overall, primary MCS tumours, especially those greater than 5 cm or located on the trunk, should be treated with a wide local excision and followed closely to confirm no lesion recurrence or distant metastasis.