Sialadenoma papilliferum (SP) is a rare neoplasm of salivary duct origin, characterised by both exophytic squamous and endophytic ductal components. 1 Morphologically similar tumours lacking a surface exophytic component have been reported as sialadenoma papilliferum-like intraductal papillary tumours (SP-IPT). 2 Both tumours have shown a similar genetic profile, frequently harbouring BRAF p.V600E mutations. We report a case of a 71-year-old female, current smoker, who presented with a slow growing, right soft palate, 5 mm ulcerated lesion to the oral maxillofacial surgical clinic. An incisional biopsy of the lesion was performed. Microscopy revealed an endophytic, ductal papillary proliferation including micropapillary architecture and a few cyst-like spaces contiguous with surface epithelium via a short tract. The lining epithelium comprised a mix of columnar ductal and mucinous cells, abruptly transitioning to squamous epithelium near the surface. Differential diagnoses included SP, SP-IPT, intraductal papilloma, intraductal carcinoma, cystadenoma and low grade mucoepidermoid carcinoma. The tumour showed luminal CK7 and BRAFVE1 immunopositivity with an intact myoepithelial layer highlighted by p63 and S100. Fluorescence in situ hybridisation studies showed no disruption of MAML2. A diagnosis of SP-IPT was made. Accurate morphological analysis and use of ancillary studies were essential in reaching the diagnosis.
Boon et al. (Sun,) studied this question.