Parosteal Lipoma of the Thigh: A Report of a Rare Case and Review of the Literature.

Parosteal lipomas are rare benign mesenchymal tumors consisting of mature adipocytes arising in close association with the periosteum. It accounts for less than 0.3% of all lipomas and is most often seen in the long bones of the extremities. These lesions are slow-growing and often asymptomatic, which can delay clinical recognition. Due to their proximity to bone, they can occasionally cause cortical remodeling or reactive bone changes, making radiological evaluation essential for an accurate and definitive diagnosis. We report a case of a 51-year-old female who presented with a gradually progressive swelling over the medial aspect of the proximal thigh for one year. The patient denied any prior history of trauma or any surgical procedure. On local examination, the swelling was soft in consistency, non-tender, and immobile. The overlying skin was normal, with no ulceration, erythema, or discoloration, and there was no associated warmth or fluctuation. On functional assessment, there was no restriction in joint movements, and neurovascular examination of the limb was normal. Routine laboratory investigations were within normal limits.  Parosteal lipomas are rare entities that can be clinically mistaken for other soft-tissue or periosteal masses. Their characteristic attachment to the bone surface differentiates them from subcutaneous lipomas. Imaging modalities such as MRI play a crucial role in delineating their composition and relationship to adjacent structures. Surgical excision remains the treatment of choice, with an excellent prognosis and negligible recurrence risk. This report highlights a rare presentation of parosteal lipoma of the thigh in a 51-year-old female. Imaging findings can aid in timely diagnosis, prevent misclassification as a malignant lesion, and guide appropriate management.