Adipocytic Tumors

Adipocytic Tumors

G. Petur Nielsen, MD

Andrew E. Rosenberg, MD

An axial CT scan of a parosteal lipoma shows a lowdensity mass arising on the surface of the rib and involving the paraspinal soft tissues of the thoracic spine. The density of the tumor is similar to subcutaneous fat. The linear densities within the mass represent septations.

This surface lipoma shows a well-circumscribed, lobulated bright yellow mass arising on the surface of the rib (parosteal lipoma). The underlying cortex is intact and there is no involvement of the underlying bone.



  • Liposarcoma: Well-differentiated liposarcoma (WDL), myxoid/round cell liposarcoma (MLPSA)


  • Lipoma: Intramedullary lipoma, intracortical lipoma, ossifying lipoma, parosteal lipoma


  • Liposarcoma

    • Extremely rare primary malignant neoplasm of bone with a phenotype that recapitulates fat

  • Lipoma

    • Benign neoplasm of mature adipocytes that, when involving bone may arise within the bone, cortex, or on its surface (parosteal)



  • Etiology is unknown for lipoma and liposarcoma

  • No predisposing factors are known



  • Incidence

    • Liposarcoma of bone

      • Very rare

      • Most cases are in the form of single case reports

    • Lipoma of bone

      • Intraosseous lipomas are uncommon and account for < 0.1% of primary bone tumors

  • Age

    • Liposarcoma

      • Occurs in all age groups

      • Majority of patients are adults

    • Lipoma

      • Intraosseous lipomas occur over a wide age range, 2nd-8th decades; most patients are approximately 40 years old at time of diagnosis

      • Parosteal lipoma usually develops during adulthood; most patients in 5th-6th decades of life at time of diagnosis

  • Gender

    • Liposarcoma

      • Slightly more common in males

    • Lipoma

      • Intraosseous lipoma affects males more frequently than females

      • Parosteal lipoma also has slight male predominance


  • Liposarcoma

    • Usually develops in long tubular bones, most commonly tibia and femur

    • Can arise in diaphysis, metaphysis, or epiphysis

  • Lipoma

    • Vast majority of intraosseous lipomas are intramedullary and arise in metaphyseal regions of long tubular bones

    • Frequently arise in femur, tibia, fibula, and calcaneus

    • Have also been described in the pelvis, vertebrae, sacrum, skull, mandible, maxilla, and ribs

    • Rare cases are intracortical in origin

    • Parosteal lipoma generally develop on diaphyseal surface of long tubular bones, including femur, humerus, and tibia


  • Liposarcoma

    • Painful mass

  • Lipoma

    • May be asymptomatic and found incidentally

    • Can be painful

    • May be detected as a visible or palpable mass

    • Rarely presents with a pathologic fracture


  • Liposarcoma

    • Generally, behavior of tumor correlates with its histologic grade

    • Well-differentiated liposarcoma has best prognosis

    • Pleomorphic liposarcoma has worst prognosis

  • Lipoma

    • Excellent

    • Rarely recurs

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Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Adipocytic Tumors

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