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AT-A-GLANCE
Lipogenic neoplasms represent the most frequent mesenchymal neoplasms.
Lipogenic neoplasms include benign neoplasms (eg, lipoma, angiolipoma), intermediate, locally aggressive, nonmetastasizing neoplasms (eg, atypical lipomatous tumor), and clearly malignant lesions (eg, pleomorphic liposarcoma).
Anatomic site, depth, and size are responsible for striking differences in regard to incidence, morphology, and prognosis.
The clinical presentation of lipogenic neoplasms is usually nonspecific.
The majority of lipogenic neoplasms is characterized by distinct cytogenetic abnormalities that may have diagnostic and therapeutic value.
Surgical excision is the treatment of choice; in cases of malignant neoplasms not amenable for complete excision radiation therapy, however, chemotherapy or target-like therapy may be used.
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Although lipogenic neoplasms represent the largest single group of mesenchymal tumors in the skin and in soft tissues, there are significant differences in regard to incidence, morphologic features, and prognosis between superficial and deep-seated lipogenic neoplasms that are important to know to avoid misdiagnosis and therapeutic errors. Whereas liposarcomas in deep soft tissues represent the most common sarcomas in adults, they are exceedingly rare in purely dermal location. Cases of spindle-cell/pleomorphic lipoma arising in the subcutis are encapsulated and occur predominantly in the neck and shoulder region of elderly male patients. In contrast, purely dermal spindle-cell/pleomorphic lipomas are ill-defined, infiltrative lesions that occur equally in both genders and show a broad anatomic distribution. The prognosis of atypical lipomatous tumor (“well-differentiated liposarcoma”) is strongly related to site and size of the neoplasms. Cases of atypical lipomatous tumor, arising in the retroperitoneum, intraabdominal, in the mediastinum and in the spermatic cord are associated with a poor clinical prognosis. These neoplasms often achieve a large size, recur repeatedly, and may cause death in a high number of cases as a result of uncontrolled local effects. In striking contrast, cases of atypical lipomatous tumor arising in surgically amenable soft tissue of the extremities usually do not recur after complete excision, and in general superficially located liposarcomas have a relatively good prognosis.
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AT-A-GLANCE
Lipoma is one of the most common benign mesenchymal neoplasms in adults.
Lipomas are composed of mature white adipocytes.
Lipomas show varying cytogenetic abnormalities.
Although surgical excision is curative, cases of intramuscular lipoma show a higher recurrence rate.
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Lipoma is the most common benign mesenchymal neoplasm and tends to occur in adults without gender predilection. Cases in childhood and multiple lesions are rare.
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Lipomas usually present as a painless, slowly growing mass involving the subcutaneous tissue of the trunk, neck, or extremities; involvement of the hands and feet is uncommon. Superficial lipomas are typically small, measuring less than 5 cm. In contrast, deep-seated intramuscular and intermuscular lipomas may reach a considerable size. Parosteal lipoma arises on the surface of bone, and so-called lipoma arborescens represents a villous lipomatous proliferation of the synovial membrane.1 Lipomas may be seen ...