Parosteal lipoma of the forearm: A case report and a literature review

RATIONALE: Parosteal lipomas are rare neoplasms comprising mature adipocytes situated in a proximity to bone. Although these tumors follow a benign course, the reactive osseous changes that may occur with such lesions might raise the suspicion of malignancy. PATIENT CONCERNS: Here we present a case of a 33-year-old male patient complaining of pain and swelling in the right anterior forearm without history of trauma. DIAGNOSIS: An magnetic resonance imaging of the region revealed a lobulated intramuscular fat intensity mass within the supinator muscle. Bony projection inseparable from the anterolateral radial diaphyseal cortex and periosteum was also seen. The radiological features suggested the diagnosis of parosteal lipoma. INTERVENTION: After the radiological diagnosis of a parosteal lipoma, the patient was offered a total surgical excision of the mass. OUTCOMES: The mass was removed successfully. Histopathology showed mature benign adipose tissue bordered by thin fibrous septa confirming the diagnosis of parosteal lipoma. Follow-up magnetic resonance imaging after 6 months did not reveal any signs of complications or recurrence. LESSONS: Distinction of the features of parosteal lipomas is needed to establish the accurate diagnosis, discriminate it from malignant lesions, predict potential neurovascular compromises, and follow up until a curative action is planned.