PMC8013534_01
(a) MRI shows subtle T2 hypodense, T1 intermediate lesion at the interpolar renal hilum of left native kidney measuring up to 2.6 cm. (b) CT urogram shows a questionable heterogeneous enhancement within the left native renal pelvis (arrow). (c) Well-circumscribed mass in renal sinus in the background of left atrophic native kidney. (d) Low magnification (20x) shows mature adipose tissue and hematopoietic elements. (e) Higher magnification (100x) shows normal hematopoietic elements, such as megakaryocytic, erythropoietic, and granulopoietic cell lineages dispersed within adipose tissue.
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fig1-2050313X211004799
An abdominal magnetic resonance imaging (MRI) with and without contrast showed a subtle T2 hypointense, T1 intermediate lesion at the interpolar renal hilum measuring up to 2.6 cm demonstrating mild early enhancement, diffusion restriction, and delayed washout, concerning for renal cell carcinoma or less likely urothelial carcinoma of renal pelvis (Figure 1(a)). CT urogram showed a questionable heterogeneous enhancement within the left renal pelvis (Figure 1(b)). Gross pathologic examination of the resected native kidney revealed an atrophic kidney with a well-circumscribed, non-encapsulated, tan-brown mass in the renal sinus adipose tissue measuring 3.0 cm x 2.5 cm x 1.7 cm (Figure 1(c)). Histologic examination of the mass showed mature adipose tissue admixed with benign hematopoietic elements representing all three hematopoietic cell lineages diagnostic for extra-adrenal myelolipoma (Figure 1(d) and (e)).