Abstract
Porocarcinoma (synonym: malignant eccrine poroma) is a rare aggressive carcinoma type with terminal sweat gland duct differentiation. The squamous variant of porocarcinoma is even less frequent and might be indistinguishable from conventional squamous cell carcinoma (SCC). We herein describe the first case of a carcinoma presenting as a primary parotid gland malignancy in a 24-year-old male without any other primary tumor. Total parotidectomy and neck dissection were performed followed by adjuvant chemoradiation. The patient remained alive and well 10 months after diagnosis. Histology showed keratinizing SCC infiltrating extensively the parotid gland with subtle poroid cell features. Oncogenic HPV infection was excluded by DNA-based testing. NGS analysis using the TruSight RNA fusion panel (Illumina) revealed a novel YAP1-MAML2 gene fusion. This gene fusion was reported recently in a subset of cutaneous porocarcinoma and poroma. This case of poroid SCC (or squamoid porocarcinoma) adds to the differential diagnosis of SCC presenting as parotid gland tumor and highlights the value of molecular testing in cases with unusual presentation.
Highlights
We present a novel case of primary parotid gland carcinoma presenting in a 24-yearold man without other primary tumor
The tumor showed predominant squamous differentiation with subtle poroid features and a YAP1-MAML2 gene fusion, detected by generation sequencing. This rare variant might have been underecognized as conventional squamous cell carcinomas (SCC) or high-grade mucoepidermoid carcinoma in the past
Relatively smaller monomorphic cells with sparse cytoplasm were seen. These “poroid” cells were reminiscent of the intermediate cells of mucoepidermoid carcinoma (Fig. 1c, d)
Summary
They represent < 1% of all cancers and 5% of all head and neck cancers [1]. The majority of squamous cell carcinomas (SCC) presenting within intraparotid lymph nodes represent metastatic SCC of the sun-damaged head and neck skin of the elderly [4]. We present a novel case of primary parotid gland carcinoma presenting in a 24-yearold man without other primary tumor. The tumor showed predominant squamous differentiation with subtle poroid features and a YAP1-MAML2 gene fusion, detected by generation sequencing. This rare variant might have been underecognized as conventional SCC or high-grade mucoepidermoid carcinoma in the past
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
