Journal of Advanced Clinical & Research Insights (2017), 4, 27–30 Journal of Advanced Clinical & Research Insights ● Vol. 4:1 ● Jan-Feb 2017 27 CASE REPORT Interstitial lipomatosis of minor salivary gland: Fight for a place with sialolipoma S. Suma, B. Veerendra Kumar, Amrita Samanta, Roopa P. Gaddagimath, Sarita Yanduri, M. G. Madhura Department of Oral and Maxillofacial Pathology, D.A. Pandu Memorial R.V. Dental College and Hospital, Bengaluru, Karnataka, India Abstract 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 non- neoplastic 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. Keywords Hypothyroidism, interstitial lipomatosis, minor salivary gland, sialolipoma Correspondence Dr. S. Suma, Department of Oral and Maxillofacial Pathology, D.A. Pandu Memorial R.V. Dental College and Hospital, No. CA37, 24 th  Main, J P Nagar I Phase, Bengaluru - 560 078, Karnataka, India. Phone: +91-98453 37252. E-mail: drsumas11@gmail.com Received 02 Jan 2017; Accepted 28 Feb 2017 doi: 10.15713/ins.jcri.152 Introduction Minor salivary glands (MSG) are small, chiefly mucous-secreting glands located in nearly all areas of the oral cavity. [1,2] Diseases of the MSG encompass a diverse set of non-neoplastic lesions, as well as benign and malignant neoplasms of varying grades. MSG neoplasms constitute 10-15% of all salivary gland (SG) neoplasms, with MSG being second most commonly involved after the parotid gland. [3-5] Palate is the preferred site followed by the lip, with a higher incidence in the upper lip than the lower. [4-6] However, literature regarding the incidence of non-neoplastic MSG lesions is scarce. Both neoplastic and tumor-like lesions of SG (including MSG) may contain adipose tissue. The latter may be a minor component of the lesion or may be entirely composed of adipose tissue. [7] Among these, interstitial lipomatosis (IL) is an overgrowth of adipose tissue throughout the SG and often associated with systemic factors and conditions, that should be histologically differentiated from sialolipoma, a neoplasm. [1,7,8] A rare case of IL of the upper lip in a hypothyroid patient is presented here, that required pathological insight and clinical correlation for diagnosis. An internet search in English literature did not reveal any cases reported of IL of the upper lip, thereby adding to the rarity of the case. Case Report A 55-year-old woman reported with a complaint of swelling in inner part of her upper lip since 10 days, which caused her ‘discomfort during eating and speaking’. On clinical examination, a diffuse, solitary “pea-sized” swelling in greatest dimension was observed, but a discrete mass could not be felt on palpation. Overlying mucosa appeared normal. There was no extraoral swelling. There was no pain or discharge from the swelling. There was no history of trauma recalled, however a fractured 21 was observed adjacent to the swelling. Medical history, revealed a history of hypothyroidism since 4 years, for which she was on regular medication. Dryness of eyes and mouth were absent. A provisional diagnosis of mucocele of upper lip was considered, and an excisional biopsy was performed. Intraoperatively, no discrete mass could be found, and hence the lesion was difficult to excise. According to the surgeons, the mass appeared more localized after injection of the local anesthetic [Figure 1a]. We received multiple, irregular whitish pink bits of soft tissue that lacked a capsule [Figure 1b]. Microscopic examination revealed clusters of SG tissue interposed between mature adipose tissue. The SGs were normal- appearing and included mucous acini and ducts. Lobules were