Clinical Course of Adrenal Myelolipoma

A Long-Term Longitudinal Follow-up Study

Oksana Hamidi; Ram Raman; Natalia Lazik; Nicole Iniguez-Ariza; Travis J. McKenzie; Melanie L. Lyden; Geoffrey B. Thompson; Benzon M. Dy; William F. Young Jr; Irina Bancos


Clin Endocrinol. 2020;93(1):11-18. 

In This Article

Abstract and Introduction


Objective: We aimed to describe clinical course of myelolipoma and to identify predictors of tumour growth and need for surgery.

Design: A retrospective study.

Patients: Consecutive patients with myelolipoma.

Results: A total of 321 myelolipomas (median size, 2.3 cm) were diagnosed in 305 patients at median age of 63 years (range, 25–87). Median follow-up was 54 months. Most myelolipomas were incidentally detected (86%), whereas 9% were discovered during cancer staging and 5% during workup of mass effect symptoms. Thirty-seven (12%) patients underwent adrenalectomy. Compared to myelolipomas <6 cm, tumours ≥6 cm were more likely to be bilateral (21% vs 3%, P < .0001), cause mass effect symptoms (32% vs 0%, P < .0001), have haemorrhagic changes (14% vs 1%, P < .0001) and undergo adrenalectomy (52% vs 5%, P < .0001). Among patients with ≥6 months of imaging follow-up, median size change was 0 mm (−10, 115) and median growth rate was 0 mm/y (−6, 14). Compared to <1 cm growth, ≥1 cm growth correlated with larger initial size (3.6 vs 2.3 cm, P = .02), haemorrhagic changes (12% vs 2%, P = .007) and adrenalectomy (35% vs 8%, P < .0001).

Conclusions: Most myelolipomas are incidentally discovered on cross-sectional imaging. Myelolipomas ≥6 are more likely to cause mass effect symptoms, have haemorrhagic changes and undergo resection. Tumour growth ≥1 cm is associated with larger myelolipoma and haemorrhagic changes. Adrenalectomy should be considered in symptomatic patients with large tumours and when there is evidence of haemorrhage or tumour growth.


Adrenal myelolipoma is a benign adrenocortical tumour composed of adipose tissue and bone marrow elements.[1,2] It is the second most common tumour of the adrenal gland reported in one out of 500–1250 autopsy cases.[3] Myelolipoma is commonly diagnosed in the fifth and sixth decade of life with no obvious sex predilection.[4–6] The pathogenesis of myelolipoma is unclear, although it is hypothesized to develop from mesenchymal cell metaplasia or as a result overstimulation by increased corticotropin (ACTH) secretion.[7,8] Increasing incidence of myelolipoma is largely attributed to widespread use of abdominal imaging, accounting for prevalence of 6%-16% of adrenal incidentalomas.[9–11] Although large myelolipomas can lead to mass effect symptoms, most myelolipomas are asymptomatic and are detected incidentally during evaluation for unrelated symptoms or cancer staging. Histopathological haemorrhagic changes are described in up to 19% of cases, whereas spontaneous tumour rupture is reported in 4.5% of myelolipomas, more commonly in large myelolipomas measuring 10–12 cm.[12] Coexisting adrenocortical tumours and congenital adrenal hyperplasia are described in 5.7% and 10% of myelolipoma cases, respectively.[12,13]

Despite high prevalence of adrenal myelolipoma, most data on longitudinal follow-up of these tumours are limited to surgical case series, with inadvertent bias of describing symptomatic and surgically treated cases. Moreover, clinical guidelines on management of adrenal tumours lack evidence-based recommendations on evaluation and management of myelolipoma.[14,15] Therefore, we aimed to provide a perspective on the natural history, management and outcomes of consecutive patients with myelolipoma, and to identify predictors of tumour growth and surgical resection.