Adrenolipoma overview

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ahmad Al Maradni, M.D. [2]

Overview

Adrenolipomas are rare benign neoplasms that histologically consist of fat and bone marrow in varying proportions. In general, they are small, unilateral, and hormonally inactive. They are rich in adipose tissue and hematopoietic elements. Most lesions are small and asymptomatic. Adrenolipomas are usually detected incidentally in autopsy or by imaging studies performed for other reasons. Most tumors are unilateral, they show no predilection to one peculiar side. Symptoms of adrenolipoma include abdominal pain, haematuria, and abdominal fullness. Surgery is the mainstay of treatment.

Historical Perspective

Adrenolipoma was first discovered by Gierke in 1905.

Classification

Myelolipomas are classified into 4 type based on their clinicopathologic patterns:

• Isolated adrenal myelolipoma
• Adrenal myelolipoma with acute hemorrhage
• Extra-adrenal myelolipoma
• Myelolipoma associated with other adrenal diseases.

Clinicopathologic patterns
Isolated Adrenal Myelolipoma
Adrenal Myelolipoma with Acute Hemorrhage
Extra-adrenal Myelolipoma
Adrenal Myelolipoma with Associated Adrenal Disease

Isolated Adrenal Myelolipoma: Myelolipomas occurring in an otherwise normal adrenal gland are the most common pattern of presentation. They are asymptomatic and are incidentally identified during the imaging investigation performed for some other reason.

Adrenal Myelolipoma with Acute Hemorrhage: Retroperitoneal hemorrhage is the most common complication occurring in adrenal myelolipoma. Isolated larger lesions (typically over 4 cm in size) and those predominantly composed of fat (greater than 50%) have a greater propensity for a hemorrhagic event.  

Extra-adrenal Myelolipoma: Myelolipomas occurring outside the adrenal gland are most commonly found in the retroperitoneum where presacral or perirenal location are reported as the most common. Patients usually have no endocrine disorder or acute hemorrhage.

Adrenal Myelolipoma with Associated Adrenal Disease: Less commonly patients with adrenal myelolipoma tend to have an endocrine disorder: hypercortisolism (Cushing syndrome) and 21-hydroxylase deficiency with adrenal hyperplasia have been reported in patients with symptomatic adrenal myelolipomas.

Pathophysiology

• Myelolipomas 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.
• 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

Causes

There are no established causes for adrenolipoma.

Differentiating Adrenolipoma from other Disease

Adrenolipoma must be differentiated from retroperitoneal liposarcoma, adrenal teratoma, and adrenocortical carcinoma.

Epidemiology and Demographics

• The incidence of adrenolipoma is approximately 0.8-4 per 100,000 individuals worldwide.
• Adrenolipoma affects men and women equally.
• Adrenolipomas are usually recognized in adults, either incidentally at ultrasound or computed topography or may present with vague abdominal symptoms if complicated by hemorrhage.

Risk Factors

There are no established risk factors.

Screening

There is insufficient evidence to recommend routine screening for adrenolipoma.

Complications

Common complications of adrenolipoma include Cushing syndrome, Conn syndrome, congenital adrenal hyperplasia and retroperitoneal haemorrhage.

Diagnosis

History and Symptoms

Symptoms of adrenolipoma include abdominal pain, haematuria, and abdominal fullness.

Laboratory Findings

There are no associated laboratory findings among the majority of patients with adrenolipoma.

Abdominal X-Ray

There are no abdominal X-ray findings associated with adrenolipoma.

CT

Abdominal CT scan may be helpful in the diagnosis of adrenolipoma.

MRI

Abdominals MRI may be helpful in the diagnosis of adrenolipoma.

Ultrasonography

On ultrasound, adrenolipoma is characterized by heterogenous mass of mixed hyper- and hypoechoic components.

Other Diagnostic Studies

Other diagnostic studies for adrenolipoma include fine needle aspiration and fluorodeoxyglucose uptake (FDG).

Treatment

Medical Therapy

There is no treatment for adrenolipoma; the mainstay of therapy is supportive care.

Surgery

Surgery is the mainstay of treatment of large adrenolipomas.

Primary Prevention

There are no preventive measurements available for adrenolipoma.