Sir,

The presence of a yellowish nodule on the tongue is a clinical situation that the clinician may be confronted with in daily practice. The knowledge of the anatomy of the tongue allows to orientate the diagnosis properly in the event of the rare consultation.

A seventy-year-old patient reported a six-year nodule, 2.5 cm in size, on a large, yellowish axis, well-limited, with a regular and roughly rounded contour and a surface covered with telangiectasias of firm consistency located on the right free edge of the tongue (Fig.1a). In addition, the absence of other cutaneous or mucous lesions was noted.

Figure 1: (a) Yellowish nodule on the tongue. (b) Histological picture of the lipoma: multiple fat lobules separated by septa.

A biopsy excision was in favor of lipoma (Fig. 1b).

Lipomas are benign tumors of the adipose mesenchyme that rarely occur in the oral cavity. They are the most common mesenchymal tumors in the human body. They account for only around 1–4% of benign tumors of the oral cavity [1].

The etiology and pathogenesis of lipomas remain unclear. Previously, it was argued that lipoblast and embryonic mesoderm proliferation were the origins of lipomas.

Two theories are currently held. The hypertrophy theory states that obesity and additional adipose tissue deposition may lead to oral lipoma formation, yet it is not widely accepted. Another theory of lipoma formation is the metaplasia theory, according to which lipoblast formation may be due to abnormal differentiation of mesenchymal cells. Trauma, hormonal influence, chromosomal abnormalities, and chronic irritation may play a role in the differentiation of dormant cells into fat cells. It is proposed that, after soft tissue injury and subsequent hematoma formation, cytokines involved in the repair process trigger the differentiation and proliferation of adipocytes [1,2].

Superficial oral lipomas may have a yellowish hue, yet deep oral lipomas may appear pink. They are often asymptomatic and may be noted after several months or years. Lipoma involves fatty tissue, thus sites on the oral mucosa with fatty tissue are the most frequently affected areas. The oral mucosa is the most common intra-oral site for lipomas. The least common sites are the tongue, floor of the mouth, retromolar region, and lips. The most affected patients are forty years of age or older.

Lipomas are common soft tissue tumors, yet few cases of lipomas of the tongue have been reported. Ours was a case of lipoma on the right lateral border of the tongue in a seventy-year-old male.

REFERENCES

1. Varma BR, Kumar KS, Verghese RS, Janardhanan M. Unusual presentation of lipoma on the tongue. BMJ Case Rep. 2020;13:e232485.

2. Tiwary AK, Lal YA, Mishra DK. Granular cell tumour:An uncommon tumour of Schwann cell origin. Our Dermatol Online. 2016;7:409-11.