Interstitial lipomatosis of minor salivary gland: Fight for a place with sialolipoma

The aim of this article is to report an uncommon lipomatous minor salivary gland (MSG) lesion of the upper lip that was diagnosed with pathological insight and clinical correlation. Differential diagnosis of fat containing salivary gland (SG) tumors will also be discussed. MSG lesions constitute a diverse group encompassing non-neoplastic lesions, benign neoplasms, and malignant neoplasms of varying grades. A rare subset among these includes the lipomatous SG lesions. Interstitial lipomatosis (IL) is an overgrowth of adipose tissue throughout the SG, that should be histologically differentiated from sialolipoma and infiltrating lipoma, which is neoplasms. The former is associated with systemic conditions while the latter is not. This case is of IL in a 55-year-old woman with hypothyroidism. A search in English literature did not reveal any cases of IL of the upper lip. The fact that SG neoplasms are more common in the upper lip than nonneoplastic lesions adds to the rarity of this case. Thus, this report adds another entity in the differential diagnosis of upper lip lesions and underlines the need to differentiate it from lipomatous neoplasms.