A 5 kg giant breast lipoma in a 40-year-old woman: a case report.

[INTRODUCTION AND IMPORTANCE] Lipomas are benign tumours composed of adipocytes surrounded by a thin fibrous capsule. Although they make up 16% of mesenchymal tumours, the occurrence of breast lipomas is uncertain. Giant lipomas, measuring 10 cm or more in diameter or weighing at least 1000 g, commonly occur in the upper back, neck, and thigh, and are rare in the breast. Given its rarity, accurately diagnosing a giant breast lipoma is crucial to prevent potential overtreatment, as it might otherwise be mistaken for a malignant tumour.

[CASE PRESENTATION] A 40-year-old woman presented with a painless, gradually enlarging left breast mass. Physical examination and imaging studies revealed a lipoma-compatible mass. Surgery was performed, and the 5 kg mass was enucleated and identified as a lipoma on histopathology. The patient had an uneventful postoperative recovery and was satisfied with the outcome of the surgery after 2 months of follow-up.

[CLINICAL DISCUSSION] Breast lipomas are more common in the 40-60 years age group, with giant lipomas occurring more frequently in the latter half of this age range. They can mimic various breast conditions, including neoplastic and non-neoplastic conditions, and are often treated with surgical excision to avoid recurrence. The location of the lipoma in the breast can be subcutaneous or intramuscular, and preserving the future pedicle of reduction mammoplasty/mastopexy is essential.

[CONCLUSION] Giant breast lipoma is an infrequent condition that can manifests as progressive enlargement of the breast, posing a diagnostic challenge due to its resemblance to various benign or malignant pathologies.