Renal leiomyoma

Renal leiomyoma, also leiomyoma of the kidney, is a very rare benign kidney tumour.

General

• Rare - estimated to represent 0.3% of treated renal tumours.

Microscopic

Features:

• Fasicular architecture.
• Spindle cells without significant atypia.

DDx:

• Angiomyolipoma - typically contain adipose tissue.
• Leiomyosarcoma - typically have at least some of the following: nuclear atypia, mitosis, necrosis.

IHC

Features:

• HMB-45 -ve.
• Desmin +ve.
• ER and PR +ve (6 of 9 cases:).

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Mass Lesion, Right Kidney, Core Biopsy:
- Benign leiomyoma with hyalinization and without atypia, see comment.
- Renal parenchyma within normal limits present.
- NEGATIVE for malignancy.

Comment:
The tumour stains as follows:
POSITIVE: desmin, SMA, ER, PR.
NEGATIVE: HMB-45.
Proliferation (Ki-67): 0%.

The tumour histology and immunoprofile is that of a leiomyoma. Renal leiomyomas are very rare lesions; a large contemporary series has only 9 cases. [1] 

Correlation with radiology is suggested.

1. Am J Surg Pathol. 2015 Mar;39(3):349-56.

Micro

The sections show tumour with a fascicular architecture and hyalinization. No adipose tissue is seen. Necrosis is not identified. Nuclear atypia is not seen. Mitotic activity is not readily apparent. Benign unremarkable renal parenchyma is present.

See also

• Leiomyoma.
• Kidney tumours.