Lipoma
Variant: Myelolipoma
Diagnostic Criteria
- Circumscribed mass composed of mature fat and bone marrow elements
- Fat component usually predominates
- May have prominent lymphoid component
- Most often occurs in adrenal
- Most common extra-adrenal site is pelvis
Differential Diagnosis
| Extramedullary Hematopoeisis | Myelolipoma |
|---|---|
| Poorly circumscribed | Circumscribed |
| Overrun fat | Fat integral to tumor |
| No prominent lymphoid component | Lymphocytes may be prominent |
| Hematologic abnormalities associated | No hematologic abnormalities |
| Lipoblastoma with Extramedullary Hematopoiesis | Myelolipoma |
|---|---|
| Immature fat cells present | No immature fat cells |
| Areas with vascular myxoid stroma | Lacks vascular myxoid stroma |
| Usually under age 10, virtually always under 20 | Usually over age 40 |
Clinical
- Usually over age 40
- May be quite large (25 cm) and multiple
- Not associated with hematologic abnormalities
- May cause symptomatic hemorrhage
- Benign
Bibliography
- Bishop E, Eble JN, Cheng L, Wang M, Chase DR, Orazi A, O'Malley DP. Adrenal myelolipomas show nonrandom X-chromosome inactivation in hematopoietic elements and fat: support for a clonal origin of myelolipomas. Am J Surg Pathol. 2006 Jul;30(7):838-43.
- Lam KY, Lo CY. Adrenal lipomatous tumours: a 30 year clinicopathological experience at a single institution. J Clin Pathol. 2001 Sep;54(9):707-12.
