MEDICAL IMAGING-CASE OF THE MONTH
Adrenal collision tumour comprised of adrenocortical carcinoma and myelolipoma in a patient with congenital adrenal hyperplasia
Marius G Pakalniskis,1 Kousei Ishigami,2 (D Brittany L Pakalniskis3 and Nobuhiro Fujita1
1 Department of Radiology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
2 Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, Nishihara-Cho, Okinawa, Japan
3 Department of Pathology, University of Iowa Hospitals and Clinics, Iowa City, Iowa, USA
Journal of Medical Imaging and Radiation Oncology
MG Pakalniskis MD; K Ishigami MD; BL Pakalniskis MD; N Fujita MD.
Correspondence
Associate Professor Kousei Ishigami, Department of Radiology, Graduate School of Medical Science, University of the Ryukyus, 207 Uehara, Nishihara-Cho, Okinawa, 903- 0215 Japan.
Email: ishigami@med.u-ryukyu.ac.jp
Conflict of interest: None.
Submitted 2 May 2019; accepted 7 September 2019.
doi:10.1111/1754-9485.12961
Summary
Adrenal myelolipoma is a benign tumour characterized by the presence of macroscopic fat. Further workup is not necessary if a diagnosis of adrenal myelolipoma is obtained via imaging. We report the first case of adrenal colli- sion tumour comprised of adrenocortical carcinoma and myelolipoma in a patient with bilateral myelolipomas and congenital adrenal hyperplasia. Com- puted tomography showed a large right adrenal mass consisting of two differ- ent components: soft tissue with peripheral heterogeneous enhancement and macroscopic fat. Imaging findings reflected features of both adrenocortical carcinoma and myelolipoma. Although this entity is rare, collision tumour con- taining an adrenocortical carcinoma component should be suspected if por- tions of an adrenal mass partially consist of peripheral heterogeneous enhancement.
Key words: Abdomen; Body CT; Uroradiology.
Case report
A 61-year-old man with a past medical history significant for pseudohermaphroditism and congenital adrenal hyperplasia (CAH) was transferred to our hospital for management of pressor-dependent shock. Subsequent laboratory workup revealed elevated 17-OH proges- terone levels and normonatremia consistent with non- salt-wasting 21-OH deficiency. In addition, autonomous adrenocorticotropic hormone (ACTH)-independent hyper- cortisolism was identified.
Abdominal computed tomography (CT) demon- strated a large, 10.3-cm right adrenal mass compress- ing the overlying right hepatic lobe upward and displacing the right kidney anteriorly. Multiple coarse intratumoural calcifications were noted. The mass consisted of areas of macroscopic fat and a heteroge- neously enhanced component (Fig. 1). A smaller, 2.9-cm fat-attenuating mass in the contralateral left adrenal gland was also seen, which was consistent with a myelolipoma. A uterus but no ovaries were noted, compatible with the history of female pseudo- hermaphroditism.
Right adrenalectomy was performed. Microscopically, the mass showed features of malignancy, including sheeted growth, pleomorphic nuclei and eosinophilic cytoplasm (Fig. 2). Tumour necrosis and atypical mitotic figures were also present. Immunohistochemistry demonstrated these cells to be positive for inhibin expression. A portion of the tumour was composed of haematopoietic elements admixed with adipose tissue. A diagnosis of adrenocortical carcinoma (ACC) with myelo- lipoma was made.
Discussion
The present case demonstrated a large adrenal tumour with heterogeneous peripheral enhancement, features suggestive of ACC.1 The presence of macroscopic fat within the tumour complicated the differential diagno- sis. Cases of ACC containing macroscopic fat have been reported2,3; however, the fatty components in these cases were embedded within heterogeneous masses. In the present patient, the fatty tissue repre- senting the myelolipoma was located at the periphery, suggesting it was a distinct component. In addition,
(a)
(b)
A
(a)
(b)
previous reports of ACC with macroscopic fat described the quantity of fatty tissue as scant, whereas the pre- sent case appeared to have a more significant fatty component.
Myelolipomas are hormonally inactive, benign tumours composed of both haematopoietic tissue and mature adipose cells. The aetiology of adrenal myelolipomas is unknown; however, studies have pos- tulated chronic stimulation by ACTH as a possible cause.4 Therefore, the present patient with CAH may have been predisposed to developing bilateral myelolipomas. In fact, patients with CAH may be at an increased risk of developing other adrenal tumours in addition to myelolipomas.5
In summary, we have presented a rare case of an ACC and myelolipoma collision tumour. Although this entity is exceedingly rare, careful analysis of each tumour compo- nent may yield an accurate diagnosis by CT.
References
1. Johnson PT, Horton KM, Fishman EK. Adrenal mass imaging with multidetector CT: pathologic conditions, pearls, and pitfalls. Radiographics 2009; 29: 1333-1351.
2. Egbert N, Elsayes KM, Azar S, Caoili EM. Computed tomography of adrenocortical carcinoma containing macroscopic fat. Cancer Imaging 2010; 10: 198-200.
3. Ferrozzi F, Bova D. CT and MR demonstration of fat within an adrenal cortical carcinoma. Abdom Imaging 1995; 20: 272-4.
4. German-Mena E, Zibari GB, Levine SN. Adrenal myelolipomas in patients with congenital adrenal hyperplasia: review of the literature and a case report. Endocr Pract. 2011; 17: 441-7.
5. Jaresch S, Kornely E, Kley HK, Schlaghecke R. Adrenal incidentaloma and patients with homozygous or heterozygous congenital adrenal hyperplasia. J Clin Endocrinol Metab. 1992; 74: 685-9.