bubble_chart Overview

Fat fleshy tumor is one of the more common types of malignant soft tissue fleshy tumors.

bubble_chart Pathological Changes

1. Macroscopic findings: Generally, the membrane is intact with relatively clear boundaries from surrounding tissues. The cut surface typically appears yellow or grayish-white and may be lobulated. Larger lesions may exhibit hemorrhage and necrosis.

2. Microscopic findings: The main observation is the presence of lipoblasts, lipoblasts at various stages of differentiation, and mature adipocytes. These neoplastic cells exhibit different morphologies depending on their stage of differentiation, but a common feature is that all types of fatty fleshy tumor cells, regardless of their differentiation level, show varying degrees of atypia.

Based on cellular composition, fatty fleshy tumors can be further classified into: ① Well-differentiated fatty fleshy tumor, also known as lipoma-like fatty fleshy tumor; ② Myxoid fatty fleshy tumor; ③ Round cell fatty fleshy tumor; ④ Pleomorphic fatty fleshy tumor; ⑤ Undifferentiated fatty fleshy tumor.

bubble_chart Clinical Manifestations

It is most commonly seen in patients aged 30 to 70, with the highest incidence around 50 years old. Men are affected more frequently than women. The condition often occurs in the limbs, especially the thighs and buttocks, as well as the upper arms, retroperitoneum, head, and neck. The lesions typically measure 3–10 cm in diameter, though retroperitoneal masses can grow larger than 20 cm. The tumors usually present as nodular or lobulated masses with a soft or slightly firm texture.

bubble_chart Treatment Measures

Surgical treatment is the first choice in the treatment of fatty fleshy tumors. Wide local excision is an effective measure to reduce recurrence and metastasis. Since lymph node metastasis of fatty fleshy tumors is rare, lymph node dissection in the drainage area is usually unnecessary.

The significance of radiotherapy has been reported in the literature, with the mucinous type of fatty fleshy tumor being more sensitive to radiotherapy. However, overall, radiotherapy is not a primary treatment for fatty fleshy tumors. We mostly use it for patients with marginal tumor resection to prevent local recurrence. For patients who can undergo radical or wide local excision, postoperative radiotherapy is of little significance.

Due to the low malignancy and low likelihood of metastasis in well-differentiated fatty fleshy tumors, chemotherapy is of little significance. For more malignant types, chemotherapy can be administered postoperatively to prevent metastasis. As there are currently no highly effective chemotherapy drugs specifically for fatty fleshy tumors, we often use combination chemotherapy. Commonly used drugs include doxorubicin (ADM), cisplatin (DDP), cyclophosphamide (CTX), and vincristine (VCR), which are meaningful for treating micrometastases before clinical metastasis is detected.

Due to the variety of histological types of fatty fleshy tumors, according to literature reports and our own experience, the prognosis of well-differentiated and mucinous types is relatively good, with a 5-year survival rate of about 80%. In contrast, the pleomorphic, round cell, and dedifferentiated types have a poor prognosis, with a 5-year survival rate of 20–50%. Metastasis occurs mainly through hematogenous spread, often to the lungs.

bubble_chart Differentiation

The final diagnosis relies on pathological examination, primarily distinguishing the tumor from the common and myxoid types of malignant fibrous histiocytoma, as well as the pleomorphic type of rhabdomyosarcoma.