Adrenolipoma pathophysiology

On gross pathology, central congested red to brown lesion, with thin cortical rim is a characteristic finding of adrenolipoma. On microscopic histopathological analysis, variable amounts of adipocytes and hematopietic cells are characteristic findings of adrenolipoma.

• Adrenlolipomas are usually less than 4 cm in size occasionally measuring more than 10 cm in size.
• Extra-adrenal sites for myelolipomas include the retroperitoneum, thorax, and pelvis.
• Usually unilateral however they can also involve both adrenals.
• One hypothesis suggests that stimuli, such as necrosis, inflammation, infection, or stress could cause adrenocortical cell metaplasia
• If chronically present these stimulants lead to the development of neoplasms.This hypothesis is supported by the increased incidence of the lesion in the advanced years of life.
• On gross pathologic examination, a cut section of a myelolipoma has a variegated appearance consisting of bright yellow areas of fat, dark red areas of hematopoietic myeloid tissue, and areas with intermixed red and yellow components.
• On histopathologic examination, myelolipomas are predominantly composed of fatty areas with interspersed hematopoietic tissue components.
• These fatty elements and hematopoietic areas may be clearly separated, or they are often intermixed.
• Tissue analysis often reveals a variable amalgamation of myeloid and erythroid cells, megakaryocytes, and occasionally lymphocytes.
• In an isolated adrenal myelolipoma, a peripheral rim of normal adrenal cortical tissue can be commonly identified distinctly from the mass.
• Rarely the myelolipomas can contain osteoid tissue in addition to the myeloid tissue.
• The hemorrhagic areas may be partly replaced by fibrotic tissue or may undergo calcification

Macroscopic examination demonstrates:^[1]

Central congested red to brown lesion, with thin cortical rim. Large lesions may contain hemorrhage or infarction.

Histological examination demonstrates:^[1]

• Variable amounts of mature adipocytes (with distended lipid vacuoles) similar to bone marrow
• Variable amounts of hematopoietic cells (including cells from myeloid, erythroid and megakaryocytic cells lines)

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