Kaohsiung Journal of Medical Sciences (2012) 28, 377e382

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ORIGINAL ARTICLE

Adrenal myelolipoma: A 10-year single-center experienceand literature review

Sz-Wen Hsu, Kenneth Shu, Wei-Ching Lee, Yuan-Tso Cheng, Po-Hui Chiang*

Department of Urology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University Collegeof Medicine, Kaohsiung, Taiwan

Received 15 February 2011; accepted 17 June 2011Available online 28 April 2012

KEYWORDSAdrenal myelolipoma;Adrenal tumor

* Corresponding author. DepartmentGung Memorial Hospital and ChangMedicine, 123, Ta-Pei Road, Niaosung

E-mail address: tuoa480713@yahoo

1607-551X/$36 Copyright ª 2012, Elsedoi:10.1016/j.kjms.2012.02.005

Abstract Adrenal myelolipoma is a rare, nonfunctioning, and benign tumor. We report ourexperience of surgically treated patients from a single institute and review the literature.Six patients (three men and three women) were diagnosed and received surgical intervention.A retrospective analysis was done by reviewing medical records. In our series, three patientswere diagnosed incidentally and the others were discovered due to symptoms. All receivedsurgery, including laparoscopic adrenalectomy. There was no recurrence. In the literaturereview, right adrenal gland was dominant and the prevalent age was from the fourth to sixthdecades. The most common symptoms were abdominal and flank pain. Adrenal myelolipoma isuncommon and easily confused with malignancy when of large size (�6 cm). Surgery may bereserved for symptomatic cases and those lesions that cannot reliably be diagnosed. Largetumors (�6 cm) can be excised surgically or laparoscopically.Copyright ª 2012, Elsevier Taiwan LLC. All rights reserved.

Introduction

Adrenal myelolipoma is a rare, nonfunctioning, and benigntumor. It was first described by Gierke in 1905 and namedby Oberling in 1929 [1]. The tumor is composed of maturefat tissue and hematopoietic tissues. Initially, some caseswere suspected to be malignant diseases such as

of Urology, Kaohsiung ChangGung University College of, Kaohsiung, Taiwan..com.tw (P.-H. Chiang).

vier Taiwan LLC. All rights reserv

liposarcoma and leiomyosarcoma in an image study. Casereports are limited, especially concerning large adrenalmyelolipoma. We report our experience of large adrenalmyelolipoma and review the literature.

Patients and methods

Data for the present series were collected from theDepartment of Urology, Chang Gung Memorial Hospital,Kaohsiung Medical Center, between 2001 and 2010. Sixpatients (three men and three women) were diagnosed andreceived surgical intervention. The initial diagnosis was

ed.

Table 1 Patient characteristics, clinical data and management.

Age Sex Presentation Imagestudy

Side Tumorsize (cm)

Management Follow-up(month)

Initial impression

44 F Incidentally CT, MRI Right 14 Reversed L incision 33 Right renal hamartoma47 F Incidentally CT Right 6 Retroperitoneoscopy 40 Right adrenal myelolipoma51 M Incidentally CT Right 9.5 Subcostal incision 51 Suprarenal lipoma or liposarcoma48 M Left palpable

massCT Left 13.5 Midline incision 114 Hamartoma D/D: liposarcoma

45 M Abdominalpain

CT, MRI Right 16.5 Subcostal incision 25 Myelolipoma, liposarcoma,leiomyosarcoma, angiomyelolipoma

51 F Abdominalfullnessand pain

CT Right 7.5 Laparoscopy 4 Right adrenal myelolipoma;D/D: renal angiomyolipoma

CT Z computerized tomography; F Z female; M Z male; MRI Z magnetic resonance imaging.

378 S.-W. Hsu et al.

based on computerized tomography (CT) and magneticresonance imaging (MRI), and a definitive diagnosis wasmade according to pathological report. A retrospectiveanalysis was performed by reviewing medical records andimage studies. We also reviewed 125 cases reported in theliterature [1e39], to which we now add six new cases.

Figure 1. A. The fat in an adrenal myelolipoma is of high signalT2-weighted images. C. Computed tomogram scan-a well defined14.0 � 10.0 � 7.0 cm.

Results

Patient mean age was 47.7 � 2.94 years (Table 1). Allpatients received image study by CT and two also receivedMRI. All tumors in our series were greater than 6 cm.The largest was 16.5 � 12.5 � 4.8 cm3. The CT image

intensity on T1- weighted. B. Intermediate signal intensity onheterogeneous adrenal mass. D. The encapsulated tumor was

Figure 2. Adipose tissue and bone marrow elements partially surrounded by epithelium of adrenal cortex and a fibrous capsulewith active bone marrow elements and extensive hemorrhaging (H&E stain, �40 and �200).

Adrenal myelolipoma 379

usually showed well-circumscribed, heterogeneous minimalenhancement with a lesion of low density. The MRI similarlydemonstrated a well-defined heterogeneous mass withareas of fat component. There was high signal intensity onthe T1-weighted images because of plenty of adiposetissue. Intermediate signal intensity on the T2-weightedimages may be found due to mixed fat and marrowtissues (Fig. 1). Three patients suffered from clinicalsymptoms, while the other three were found incidentally.Although there were some typical images in CT and MRI,only one case in our series was diagnosed definitely prior tooperation. Four patients received surgical adrenalectomy,and the others laparoscopic adrenalectomy. The surface ofthe tumor glistened with variegated discoloration. The cutsurface appeared yellowish to dark-brown in color, withsoft consistency. The pathological sections showed adrenalgland tumor comprising mature fat tissue with active bonemarrow elements and extensive hemorrhaging (Fig. 2). Theanalysis showed occurrence to be slightly more often inmales than in females, with a male-to-female ratio of

Figure 3. Most cases were diagnosed between

1.34:1. This is similar to autopsy results with a male-to-female ratio of 1.75:1 [1]. Most cases were diagnosed atbetween 40 and 69 years of age (Fig. 3). Adrenal myeloli-poma is usually unilateral. Eighty-five of 131 (64.9%)patients had tumors located on the right side, and 30 of 131(22.9%) patients had on the left side. Only 16 of 131 (12.2%)cases were bilateral. Most cases were found incidentally.The most common symptoms in this study were abdominaland flank pain (Fig. 4). Twelve cases of spontaneous rupturewere reported in the literature [29e39]. All of these weregreater than 6 cm, and the smallest was 7 cm. The spon-taneous rupture occurred in 12 of 69 (17.4%) cases in thegroup of large tumor size (�6 cm).

Discussion

The incidence of adrenal myelolipoma at autopsy variesbetween 0.08% and 0.2% [1]. The etiology of adrenalmyelolipoma is uncertain. Some reports state it to be

40 and 69 years of age. Unknown: 18 cases.

Figure 4. The most common symptoms in this study were abdominal and flank pain.

380 S.-W. Hsu et al.

associated with hypertension, atherosclerosis, diabetesmellitus, and other chronic diseases [4].

In most patient cases, adrenal myelolipoma is small andasymptomatic [5,19]. However, 68 of 131 (51.9%) cases inthis literature review had clinical symptoms. This may bedue to case recruitment. All tumors in our series werelarger than 6 cm. In our series, two of six patients sufferedfrom abdominal pain prior to operation. Logically, largeradrenal myelolipoma should exhibit symptoms moreclearly, and our data revealed that the size of the adrenalmyelolipoma is correlated with symptoms (Table 2). Atleast in our cases, surgery does relieve symptoms. Althoughthere are no data regarding the relief of symptoms aftersurgery, we do believe surgery can be useful in symptom-atic patients.

Recently, clinical diagnosis has usually been based on theabdominal CT because it is fast, is readily available, andprovides spatial resolution as well as differentiates tissuesby different CT Hounsfield units (HU). The typical CT find-ings of these cases were well-defined lesions of heteroge-neous and low-density tissue. Differential diagnoses includeretroperitoneal lipoma, retroperitoneal liposarcoma, retro-peritoneal leiomyosarcoma, extra-renal angiomyolipoma,and primary or metastatic adrenal malignancy. In both ourseries and some other studies, it was sometimes initiallyimpressed to be malignant disease such as liposarcoma

Table 2 Demographic and clinical data of the patient.

Size (cm) Male

Symptom No symptom

Left (n) Right (n) Left (n) Right (n)

0e6 2 4 11 126e10 1 9 2 610e20 2 7 2 520e30 0 3 1 230e40 0 2 1 040e50 1 0 0 0

Note: total, 112 cases; bilateral, 15 cases; and unknown, 19 cases.

and leiomyosarcoma. Accurate preoperative diagnosis ofadrenal myelolipoma may be difficult because there are nospecific imaging criteria to diagnose it. Malignancy could notbe ruled out in half of our patients. Definitive diagnosis ofadrenal myelolipoma depends on cytological or histologicalevaluation [8].

Fine needle aspiration or biopsy is the ultimate methodfor diagnosis. However, unwanted fine needle biopsy mayresult in complications with adrenal tumors. Adrenal mye-lolipoma has a classic appearance, and some believe thatthis might be sufficient for diagnosis. Therefore, carefuljudgment should be made according to the patient’sgeneral condition and preferences. Management of adrenalmyelolipoma is usually conservative because the tumors aregenerally asymptomatic and rarely show spontaneousbleeding if the tumor is small. Once adrenal myelolipomais diagnosed, regular follow-up with sonography or CT isrecommended and surgery is reserved for symptomaticcases. Some studies suggest surgical intervention forsymptomatic tumors, growing tumors, or tumors largerthan 10 cm to reduce the risk of developing abdominal painor life-threatening hemorrhage [8]. From the reviewedpapers, 12 of 70 (17.1%) cases whose tumor size wasgreater than 6 cm experienced spontaneous rupture.Therefore, elective surgery can prevent more severesymptom presentation and life-threatening progression,

Female Symptom(%)Symptom No symptom

Left (n) Right (n) Left (n) Right (n)

1 5 3 11 24.45 2 3 6 503 6 4 3 56.30 2 0 0 62.50 0 0 0 66.70 0 0 0 100

Adrenal myelolipoma 381

and can allow accurate diagnosis in patients with tumorslarger than 6 cm.

Castillo et al. [5] advocated laparoscopic adrenalec-tomies for myelolipoma. They also mentioned that tumorsize did not preclude the indication for laparoscopicapproach even if the size was greater than 5 cm (the largestone was 14 cm). We agree with this concept, and two of ourcases received laparoscopic adrenalectomy. In our series,the largest size was 7.5 cm for laparoscopic interventionand it also had a similar result.

Conclusion

Traditionally, this benign tumor will be treated conser-vatively. It is unclear as to the indication of operation forpatients with the radiologic features of these tumors todistinguish these tumors reliably from their malignantcounterparts. In the current study, we hope to offerpreliminary evidence concerning the benefit of surgery.Surgery may be reserved for symptomatic cases and thoselesions that cannot be distinguished reliably. Electivesurgery is also recommended for prevention of sponta-neous rupture in the group whose tumor size was greaterthan 6 cm. Furthermore, minimally invasive laparoscopicsurgery may not only offer an alternative choice oftreatment, but encourage patients to receive an opera-tion as well. Surgery still has its role in the managementof adrenal myelolipoma, although it is a benign tumor.Further research is needed to establish an accurate treat-ment protocol.

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