| Images of Musculoskeletal Oncology |
| Lipoma |
| A 75 year old male has had a right upper arm mass for 25 years. He has had intermittent discomfort during the past few months. No recent growth of the mass has been noted. |
| The routine radiograph reveals a large soft tissue mass in the upper arm whose density is less than that of the adjacent muscle, and the same as the density of the subcutaneous fat. Some phleboliths are also noted in the soft tissue. |
| The presence of phleboliths suggested the diagnosis of giolipoma; however, the absence of pain is against the diagnosis of angiolipoma. |
| The MRI demonstrates the large soft tissue mass, with the same density of the adjacent subcutaneous fat. |
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| The photomicrograph of the excisional biopsy reveals the mature adipose tissue with a small amount of fibrous tissue. Only a rare large nucleated cell is noted. The diagnosis is lipoma of the arm, classified as latent. No evidence of malignancy was seen in this large tumor. |
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| Learning Issues: 1. The diagnosis of lipoma is usually made clinically. However, if the tumor mass begins to grow, be suspicious of a more aggressive lesion. 2. Routine radiographs or MRI may confirm that the soft tissue lesion is made of fat, and may be useful. 3. The differential diagnosis is important, since liposarcoma is one of the most common soft tissue sarcomas. Also consider the possibility of atypical lipoma, which tends to recur, or liposarcoma, which may metastasize. A thorough search of the entire resected specimen for possible areas of dedifferentiated liposarcoma should be done. |
| Images of Musculoskeletal Oncology |
| University at Buffalo Department of Orthopaedics |