Difference between revisions of "Adrenal myelolipoma"
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Revision as of 14:24, 20 September 2019
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Adrenal myelolipoma is a benign tumor of the adrenal gland. It mainly consists of mature adipose tissue and intermixed myeloid tissue. Adrenal myelolipoma are the second most common cause of adrenal incidentillomas and make up almost 10% of it. Rarely, myelolipomas are encountered outside the adrenal glands and are termed as extra adrenal myelolipomoas.
Adrenolipoma was first discovered by Gierke in 1905.
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.
|Isolated Adrenal Myelolipoma||
|Adrenal Myelolipoma with Acute Hemorrhage||
|Adrenal Myelolipoma with Associated Adrenal Disease||
- 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.
- 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
The exact causes of Adrenal myelolipoma remain unknown. However, Adrenal myelolipoma is often associated with conditions that can be considered as adrenal stimulants such as:
- Cushing's disease
- Stressful lifestyle
- Unbalanced diet
Differentiating adrenal myelolipoma from Other Diseases
Epidemiology and Demographics
- The incidence of adrenolipoma is approximately 0.8-4 per 100,000 individuals worldwide.
- The increased prevalence of adrenal myelolipomas is due to increased detection because of wider accessibility of computed tomography (CT) and magnetic resonance imaging (MRI) scans.
- 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.
- Adrenal myelolipomas are the second most common adrenal incidentalomas comprising of 6-16% of adrenal incidentalomas.
- They have an approximate autopsy prevalence of 0.08% to 0.2%.
- They are usually recognized in adulthood with a medican age of diagnosis around 51 years. There is no gender predilection.
- There may be a slight right sided predilection as reported by some studies.
There are no established risk factors for Adrenal myelolipoma.
There is insufficient evidence to recommend routine screening for Adrenal myelolipoma.
Natural History, Complications, and Prognosis
Diagnostic Study of Choice
The diagnosis of Adrenal myelolipoma is made when
History and Symptoms
The most common presenting symptoms for adrenal myelolipomas are as follows:
- Abdominal pain
- Hypochondrial pain
- Flank pain
- Abdominal mass
Rarely, dyspnea, back pain, fever, weight loss, and virilization can be the presenting symptoms of adrenal myelolipomas.
Common physical examination findings of Adrenal myelolipoma include
There are no ECG findings associated with Adrenal myelolipoma.
There are no x-ray findings associated with Adrenal myelolipoma.
Echocardiography or Ultrasound
- Myelolipoma has the typical appearance of a hyperechoic mass with intermixed hypoechoic regions.
- Echogenicity is mainly determined by the variable proportions of the constituent elements in the lesion. The areas of intermixed fatty and myeloid tissue are the most echogenic, whereas regions of pure fat may appear hypoechoic.
- Because of inhomogeneous architecture, myelolipomas often have heterogeneous echogenicity.
- Calcification foci appear hyperechoic with acoustic shadowing.
- Myelolipoma has vague and no appreciable margins due having almost the same echogenicity as surrounding retroperitoneal fat.
- Hemorrhage alters the sonographic picture, with hemorrhagic areas appearing hypoechoic compared with fat
Abdominal CT scan may be helpful in the diagnosis of Adrenal myelolipoma. Findings on CT scan suggestive of/diagnostic of Adrenal myelolipoma include
There are no MRI findings associated with Adrenal myelolipoma.
Other Imaging Findings
There are no other imaging findings associated with Adrenal myelolipoma.
Other Diagnostic Studies
There are no other diagnostic studies associated with Adrenal myelolipoma.
There is no treatment for Adrenal myelolipoma; the mainstay of therapy is supportive care.
Surgery is not the first-line treatment option for patients with Adrenal myelolipoma. Surgery is usually reserved for patients with either
- Surgery is the mainstay of treatment of large adrenolipomas. Management of adrenal myelolipoma is decided based upon the size of lesion and presence of symptoms.
- Small lesions measuring less than 5 cm, and those who are asymptomatic are usually monitored via imaging over a period of one to two years.
- Symptomatic tumors or myelolipomas larger than 7 cm should undergo elective surgical excision.
- The approach is based on the reported incidence of life-threatening emergencies caused by spontaneous rupture and hemorrhage within large lesions.
- Conventional or endoscopic access may be chosen according to the size of the tumor.
- Mini-invasive and endoscopic techniques are best utilized for smaller-sized lesions, depending on the expertise of the operator.
- Conventional methods including transabdominal, lumbar, subcostal or posterior access laparotomy operations have all been described in the literature.
- An extraperitoneal approach is preferable as it leads to quicker recovery of the patient and lesser postoperative complications.
- The midline approach is indicated for masses larger than 10 cm or in cases where there are adhesions and infiltration of the surrounding structures.
- Follow up is mandatory regardless of which surgical method has been employed.
There are no established measures for the primary prevention of Adrenal myelolipoma.
There are no established measures for the secondary prevention of Adrenal myelolipoma.
- Decmann Á, Perge P, Tóth M, Igaz P (2018). "Adrenal myelolipoma: a comprehensive review". Endocrine. 59 (1): 7–15. doi:10.1007/s12020-017-1473-4. PMID 29164520.
- Lam AK (2017). "Lipomatous tumours in adrenal gland: WHO updates and clinical implications". Endocr Relat Cancer. 24 (3): R65–R79. doi:10.1530/ERC-16-0564. PMID 28143811.
- "StatPearls". 2019. PMID 28613782.