Low-fat and fat-free spindle cell lipomas in the oral cavity: Immunohistochemical analysis and review of the literature.

The low-fat and fat-free spindle cell lipomas (SCLs) are rare and often mistaken for other benign and malignant morphological mimics, because of the fact that the diagnosis relies on its non-lipogenic component analysis. Here, we report the clinicopathological features of two oral SCLs (low-fat and fat-free variants). Both lesions presented clinically as an asymptomatic nodule, which initially yielded diagnostic difficulties on the morphological analysis alone. One case was diagnosed as low-fat SCL on the lower lip in a 29-year-old man, and the other as fat-free SCL on the buccal mucosa in a 46-year-old man. In both cases, immunohistochemistry showed strong positivity for CD34 and, remarkably, retinoblastoma (Rb) protein was deficient. Mast cell (MC) tryptase and toluidine blue stain highlighted numerous MCs distributed throughout all tumor stroma. Alpha-SMA and desmin were negative. S100 evidenced scarce adipocytes only in the low-fat SCL case. Conservative surgical treatment was performed and no recurrence was noticed in about 2-year of follow-up in both cases. Because of the potential pitfalls, careful morphological analysis of the tumor stroma in the low-fat/fat-free SCL diagnosis, supported by immunohistochemistry (especially CD34, Rb and MC tryptase), is strongly recommended. To the best of our knowledge, these are the first and second cases reported of fat-free and low-fat SCL in the oral cavity.

Multicentre retrospective study of 97 cases of intraoral lipoma.

BACKGROUND: Lipomas are benign neoplasms derived from adipose tissue that are unfrequently found in the oral cavity. The objective of this study is to identify the main clinicopathological characteristics of this tumour in a case series of oral lipomas (OL) in a population from Spain and Brazil. MATERIAL AND METHODS: A multicentre retrospective observational study was conducted in collaboration with the Oral Pathology Unit of the São Paulo State University (UNESP), São José dos Campos, in Brazil, and the Oral Medicine and Pathology Units of the University of Santiago de Compostela (USC) and the University of the Basque Country (UPV/EHU) in Spain. RESULTS: This multicentre series consists of a total of 97 of OL cases, 31 (32%) of which correspond to Spain, and 66 (68%) to Brazil with an overall prevalence of 0.33%. The average age of the patients is 56.44 years old, with a range of 10-92 (SD = 15.52). Buccal mucosa was the most frequent location (42.3%). Cases from Spain coexisted with other lesions in a significant number of cases, 12.9%, vs Brazil, 1.5% (P = 0.018). According to the progression time, Brazil has an average of 60.35 months (CI: 27.20-93.51), compared to 5.41 months in Spain (CI: 3.17-7.65) (P = 0.022). Average size is 12.55 mm (SD = 11.06), ranging from 2 to 75 mm. A positive correlation is also seen between the increase in the lesion size and a greater progression time (CC = 0.367; P = 0.008). CONCLUSIONS: Correct differential diagnosis of the clinical lesion is key, followed by a good histopathological study, to achieve the final diagnosis.

Spindle cell lipoma of the tongue: A case report of unusual occurrence.

Spindle cell lipoma (SCL) is a benign lipomatous tumor predominantly occurring at the posterior neck and shoulder area. Face, forehead, scalp, cheek, perioral area, and upper arm are less common sites. In oral cavity, it is a relatively uncommon neoplasm, particularly in tongue, which is relatively devoid of fat cells. We present a case report of SCL located on the left lateral border of the tongue in a 64-year-old Caucasian female patient with diabetes mellitus type 2 and arterial hypertension.