Mucoepidermoid Carcinoma Associated with an Intercalated Duct Lesion: Precursor or Coincidence?

BACKGROUND

Mucoepidermoid carcinoma (MEC) typically occurs in isolation. We report an unusual case of MEC coexisting with an intercalated duct lesion (IDL), both harboring MAML2 rearrangements.

CASE PRESENTATION: An 82-year-old male with a left parotid mass underwent superficial parotidectomy.

METHODS

Microscopic examination of immunohistochemical stains and fluorescence in situ hybridization (FISH) studies were performed.

RESULTS

The parotid demonstrated an intermediate grade MEC and an adjacent IDL with the typical abluminal ΔNp63 (p40) and ductal SOX-10 immunopositivity, but absent LEF-1 and nuclear β-catenin staining. FISH confirmed MAML2 rearrangements in both lesions.

CONCLUSION

This case expands the spectrum of IDL-associated tumors and suggests IDLs may serve as MEC precursors.