|Year : 2012 | Volume
| Issue : 2 | Page : 124-126
Adrenal myelolipoma: A rare case report
Vissa Shanthi, Nandam M Rao, Balekoduru Chaitanya, Baddukonda A. R. Krishna, Kuppili V. M. Mohan
Department of Pathology, Dr. NTR University of Health Sciences, Vijayawada, Narayana Medical College, Nellore, Andhra Pradesh, India
|Date of Web Publication||11-Jul-2012|
Flat No. 301, Anjani SVGK Towers, Sri Hari Nagar, Ramalingapuram, Nellore, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Adrenal myelolipoma is a rare adrenal gland benign tumor composed of mature adipose tissue and hematopoietic tissue. Very few cases have been reported. We report a case of 19-years-old female who presented with complaint of pain in the right lumbar region. Ultrasound abdomen showed right suprarenal mass. CT scan abdomen revealed a right adrenal gland measuring 6.4 × 4.3 × 5.5 cms with heterogenous attenuation. Contrast enhanced computerized tomography (CECT) abdomen showed right adrenal mass containing both fat and soft tissue elements, suggesting the possibility of myelolipoma. The mass was surgically removed and on histopathological examination, it was diagnosed as myelolipoma of right adrenal gland. Awareness regarding this entity is very essential to exclude surgical exploration or extensive surgery.
Keywords: Adrenal gland, myelolipoma, hematopoietic cells
|How to cite this article:|
Shanthi V, Rao NM, Chaitanya B, Krishna BA, Mohan KV. Adrenal myelolipoma: A rare case report. J NTR Univ Health Sci 2012;1:124-6
| Introduction|| |
Adrenal myelolipoma is an uncommon benign tumor composed of mature adipose tissue and hematopoietic cells. They are found incidentally at autopsy or through computerized tomography (CT) scan done for other reasons.  The incidence of myelolipoma is 0.08%-0.4%, based on autopsy series.  Adrenal myelolipoma accounts for 7% to 15% of all adrenal "incidentalomas."  Extra adrenal sites for myelolipomas include pelvis, retroperitoneum, and thorax.  Adrenal myelolipomas are hormonally inactive though sometimes they co-exist with primary aldosteronism, congenital adrenal hyperplasia (CAH), pheochromocytoma, adenoma, and Cushings syndrome. Most of these patients are asymptomatic, occasionally may present with abdominal pain due to either large size or from spontaneous hemorrhage when predominantly composed of myeloid tissue. Awareness regarding this rare entity is essential to avoid an extensive surgery.
| Case Report|| |
A 19-years-old female presented with pain in the right lower abdomen radiating to the back since 1 year. On clinical examination, there was no significant finding. Hematological parameters were within normal limits. 24 hour urinary metanephrine was 7.022 micromol/24 hours, and cortisol was 205 nmol/L. Ultrasonography revealed a hyperechoic area in the suprarenal region. Computerized tomography (CT) scan showed right adrenal gland measuring 6.5 × 4.3 × 5.5 cms with heterogenous attenuation. Soft tissue density (45 to 55 HU) and hyperdense areas were noted within the gland. Post-contrast study shows heterogenous enhancement of the solid component. Contrast enhanced computerized tomography (CECT) abdomen showed well-defined lesion with central soft tissue attenuation (38-42 HU), and peripheral fat attenuation (-52 to -56 HU) measuring 6.4 × 3.3 cms was noted in the right suprarenal region. Post-contrast study shows mild enhancement (40-46 HU) of the lesion. Right adrenalectomy was performed under general anesthesia, and the specimen was sent for the histopathological examination. On gross examination, the specimen was a globular mass measuring 6.4 × 5.3 × 4.2 cm and weighing 83 gms. External surface was smooth, grayish-brown in color. Cut surface was dark brown with yellowish areas [Figure 1]. Microscopy revealed adrenal tissue at the periphery [Figure 2] beneath, which was seen a mass composed of varying proportions of adipose tissue admixed with areas of mature and immature hematopoietic tissue containing erythroid, myeloid, megakaryocytic elements, and lymphocytes [Figure 3] and [Figure 4]. There was no evidence of any other associated elements like pheochromocytoma, adreno-cortical hyperplasia, or adenoma on microscopic examination. A histological diagnosis of myelolipoma was offered.
|Figure 1: Cut surface of Adrenal myelolipoma showing dark brown and yellowish areas|
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|Figure 2: Adrenal tissue at the periphery beneath which is seen a mass composed of varying proportions of adipose tissue admixed with areas of hematopoietic tissue (H&E, ×40)|
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|Figure 3: Section showing varying proportions of adipose tissue mixed with areas of hematopoietic tissue containing erythroid, lymphoid, myeloid, and megakaryocytic elements (H&E, ×100)|
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|Figure 4: Section showing adipose tissue mixed with areas of hematopoietic tissue containing erythroid, lymphoid, myeloid, and megakaryocytic elements (H&E, ×400)|
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| Discussion|| |
Gierke in 1905 first described adrenal myelolipoma and afterwards in 1922, the name myelolipoma was given by Oberling.  Pathogenesis of adrenal myelolipoma remains doubtful. Autonomous proliferation of stem cell during embryogenesis, adrenal cortical cell degeneration, and metaplasia of mesenchymal cells are the proposed theories. Among these, the metaplasia of mesenchymal cells is the most recognized theory.  Adrenal myelolipoma has been reported in 5 th to 7 th decade of life. It occurs in both genders with female predominance. Right adrenal is more commonly involved than left. They are generally unilateral, smaller and measure less than 5 mm in diameter.  Occasional giant adrenal myelolipoma has been reported. The largest reported tumor is 6 kg in weight.  Most adrenal myelolipomas are asymptomatic, and few cases present as abdominal pain, hematuria, and constipation. Large tumors may cause traumatic rupture of the adrenal gland leading to hemoperitoneum or spontaneous hemorrhage.
Adrenal myelolipoma has been reported to coexist in association with congenital adrenal hyperplasia. Due to 21 hydroxylase or 17 hydroxylase deficiency, it is believed that excess ACTH secretion over a long period may stimulate myelolipomatous alteration in adrenal gland. The myelolipomatous tissue can replace either the tumorous or hyperplastic adrenocortical cells or may simply represent secondary degenerative changes. Differential proliferation of the undifferentiated mesenchymal stem cells of adrenal cortex into myeloid and adipose tissue in response to infection, stress, and necrosis has been the projected view for etiopathogenesis. 
Fine needle aspiration cytology is a recommended and reliable method for diagnosis of myelolipoma. The aspirate is cellular and shows mature adipose tissue fragment with many trilineage hematopoietic cells with a bloody background. This appearance mimic's red bone-marrow specimens. 
Demonstration of hypodensity within an adrenal mass is virtually diagnostic of myelolipoma by CT scan. Biochemically, a non-functioning radiolucent solid adrenal mass by CT scan with no neovascularity on angiography is most likely a myelolipoma. 
4 clinicopathologic patterns described by Kenny et al. include isolated adrenal myelolipoma without other disorders, myelolipoma with hemorrhage, more common in larger lesion (diameter > 10 cm), extra-adrenal myelolipomas being similar to adrenal myelolipomas, found most often in the retroperitoneum, and myelolipomatous foci within other adrenal pathologic conditions, which present smaller, lower fat content, and are more heavily calcified.
Generally, the gross features of myelolipoma show yellow areas with the appearance of adipose tissue alternating with hemorrhagic foci composed of bone marrow tissue. The characteristic microscopic appearance of adrenal myelolipoma is composed of bone marrow elements and mature fat. Differential diagnosis for myelolipoma includes lipoma, liposarcoma, angiomyolipoma, retroperitoneal sarcomas, adrenal carcinoma, and adenoma. Myelolipomas are to be differentiated from extramedullary hematopoiesis, which is associated with hepatosplenomegaly, anemia, infiltrative disease of bone marrow, and skeletal abnormalities. In our case, patient presented with generalized abdominal pain. On ultrasound and CT scan, a large mass was found over right renal area. It was 6.5 × 4.3 × 5.5 cms in size. Surgery was planned, and mass was removed. On gross examination, the tumor had dark brown to yellowish in appearance. Microscopically, the tumor was composed of mature lipomatous areas with presence of hematopoietic cells (erythroblasts, granulocytes, and megakaryocytes). The management of incidental myelolipoma is still controversial. Myelolipomas less than 4 cms diameter should be monitored, whereas those over 10 cm require surgical removal as there is a risk of retroperitoneal bleeding.
| Conclusion|| |
Adrenal myelolipoma is a rare entity, not encountered frequently. Awareness regarding this entity is very much essential to exclude surgical exploration or extensive surgery.
| References|| |
|1.||Chakraborthy J, Paul PCh, Gumta MK, Ghosh G, Goswamy B. Adrenal myelolipoma--Report of a case. J Indian Med Assoc 2006104:148-9. |
|2.||Po-Chun Lin, Fei-Shih Yang. Bilateral Giant adrenal myelolipomas a case report and literature review. Chin J Radiol 2008;33:261-4. |
|3.||Kloss RT, Gross MD, Francis IR, Korobkin M, Shapire B. Incidentally discovered adrenal masses. Endocr Rev 1995;16:460-84. |
|4.||Patel VG, Babolola OA, Fortson JK, Weaver WL. Adrenal myelolipoma: Report of a case and review of literature. Am Surg 2006 ;72:649-54. |
|5.||Ong k, Tan KB, Putti TC. Myelolipoma within a non-functional adrenal cortical adenoma. Singapore Med J 2007;48:e200-2. |
|6.||Han M, Burnett AL, Fishman EK, Marshall FF. The natural history and treatment of adrenal myelolipoma. J Urol 1997;157:1213-6. |
|7.||Bhansali A, Dash RJa, Singh SKb, Behra Ac, Singh Pd, Radotra Bde. Adrenal myelolipoma profile of six patients with a brief review of literature. International Jr of Endo and metabolism 2003 Mar;vol1,No1. |
|8.||Olsson CA, Krane RJ, Klugo RC, Selikowitz SM. Adrenal myelolipoma. Surgery 1973;73:665-70. |
|9.||Desai SB, Dourmashkin L, Kabakow BR, Leiter E. Myelolipoma of the adrenal gland: Case report, literature review and analysis of diagnostic feature. Mt Sinai J Med 1979;46:155-9. |
|10.||Chariklei Destouni, Foteini Karasavvidou, Kalliopi Pazaitou, Anastasios Vellis, Heraklis Vainas. Adrenal myelolipoma diagnosed by fine needle aspiration biopsy. Archive of Onchology 2001;9(3):185. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4]