Kidney tumor

Benign adult tumors

Leiomyoma


Editorial Board Member: Debra L. Zynger, M.D.
Deputy Editor-in-Chief: Maria Tretiakova, M.D., Ph.D.
Alcino Pires Gama, M.D.
Bonnie Choy, M.D.

Last author update: 12 July 2022
Last staff update: 12 July 2022

Copyright: 2003-2022, PathologyOutlines.com, Inc.

PubMed Search: Kidney leiomyoma

Alcino Pires Gama, M.D.
Bonnie Choy, M.D.
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Cite this page: Gama AP, Choy B. Leiomyoma. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/kidneytumorleiomyoma.html. Accessed December 10th, 2022.
Definition / general
  • Rare benign mesenchymal tumor of the kidney arising from smooth muscle fibers of the renal capsule, renal pelvis or vascular smooth muscle of renal vessels
Essential features
  • Benign smooth muscle tumor with female predominance
  • Arises from smooth muscle fibers of the renal capsule, renal pelvis or vascular smooth muscle of renal vessels
  • Bland spindle cells in intersecting fascicles with eosinophilic cytoplasm
  • Positive for smooth muscle markers, ER and PR and negative for melanocytic markers, cathepsin K, cytokeratins, CD117, S100 and CD34
ICD coding
  • ICD-O:
    • 8890/0 - leiomyoma, NOS
    • 8897/1 - smooth muscle tumor of uncertain malignant potential
  • ICD-10: D30.0 - benign neoplasm of the kidney
  • ICD-11: 2E86.1 - leiomyoma of other or unspecified sites
Epidemiology
Sites
  • Kidney: renal cortex or renal capsule, less commonly in muscularis propria of the renal pelvis and smooth muscle of cortical vessels
  • Seen equally in the left and right kidney
  • More frequently reported in the lower pole of the kidney (Urol Case Rep 2017;13:3)
Pathophysiology
  • Arises from smooth muscle fibers of the renal capsule, renal pelvis or vascular smooth muscle of renal vessels (J Urol 1990;143:994)
Etiology
  • Unknown
Clinical features
  • Most are asymptomatic and found incidentally
  • Larger tumors may present as a palpable mass or with flank pain or hematuria, especially if located on the renal pelvis (Pathology 2006;38:454)
Diagnosis
  • Histologic examination of tissue
  • Imaging modalities are not conclusive
Radiology description
Radiology images

Images hosted on other servers:

Ultrasound and CT

CT

CT

CT

Prognostic factors
  • Benign
  • Excellent prognosis
Case reports
Treatment
  • Surveillance or surgical resection depending on the tumor size, location and symptoms
Gross description
  • Solid, well circumscribed, tan to white with whorled and bulging cut surface
  • Focal cystic degeneration, hemorrhage or irregular calcifications may be present
  • Often solitary but occasionally multiple (Scand J Urol Nephrol 1999;33:138)
  • Most are small but the largest reported tumor measured 57.5 cm (Br J Surg 1956;43:497)
Gross images

Images hosted on other servers:

Solid, tan-white mass

Whorled, bulging cut surface

Microscopic (histologic) description
  • Arranged in intersecting fascicles
  • Spindle cells with blunt ended, cigar shaped nuclei and eosinophilic cytoplasm
  • Minimal to no nuclear pleomorphism / atypia
  • Low mitotic activity
  • No necrosis
  • Reference: Am J Surg Pathol 2016;40:1557
Microscopic (histologic) images

Contributed by Alcino Pires Gama, M.D. and Bonnie Choy, M.D.
Intersecting fascicles Intersecting fascicles

Intersecting fascicles

Bland spindle cells

Bland spindle cells

h-caldesmon

h-caldesmon

SMA

SMA

Molecular / cytogenetics description
Sample pathology report
  • Right kidney, mass, partial nephrectomy:
    • Renal leiomyoma, measuring 1.5 cm in greatest dimension (see comment)
    • Surgical margins, negative for tumor
    • Comment: The sections show a well circumscribed tumor composed of bland spindle cells in intersecting fascicles. Immunohistochemistry was performed to show positivity for SMA, desmin, h-caldesmon, ER and PR. Cytokeratin AE1 / AE3, PAX8, S100, CD117 and CD34 are negative. The overall findings support the above diagnosis of a renal leiomyoma.
Differential diagnosis
Board review style question #1

A 26 year old woman presents with back pain. CT scan located a 2.8 cm, well circumscribed, subcapsular mass in the right kidney. She underwent partial nephrectomy. Grossly, the mass was tan-white with a whorled and bulging cut surface. Microscopically, it consisted of a low grade, monotonous, spindle cell proliferation with blunt ended, cigar shaped nuclei and eosinophilic cytoplasm. No coagulative necrosis, abnormal vessels or fatty infiltration were noted. What is the most likely diagnosis?

  1. Angiomyolipoma
  2. Leiomyoma
  3. Leiomyosarcoma
  4. Sarcomatoid renal cell carcinoma
Board review style answer #1
B. Leiomyoma. Renal leiomyomas are benign tumors that arise from smooth muscle fibers of the renal capsule, renal pelvis or vascular smooth muscle of renal vessels. It is characterized by a monotonous, spindle cell proliferation with blunt ended, cigar shaped nuclei and eosinophilic cytoplasm. The low grade features are distinct from its malignant counterpart (leiomyosarcoma), as well as sarcomatoid renal cell carcinoma. The lack of mature adipose tissue and thick walled vessels makes angiomyolipoma less likely.

Comment Here

Reference: Leiomyoma
Board review style question #2
A 45 year old woman with a 2.2 cm mass in the right renal pelvis and ipsilateral hydronephrosis, underwent a radical nephrectomy. On H&E, the tumor was composed of bland spindle cells with cigar shaped nuclei. No coagulative necrosis or abnormal vessels were noted. Which of the following immunostaining profiles supports the diagnosis of leiomyoma?

  1. HMB45+, MelanA+, cathepsin K+, desmin+, caldesmon+
  2. PAX8+, CK7-, CD117+, CAIX-, vimentin-, AMACR-
  3. PAX8+, cytokeratins+, vimentin+, CD10+, CK7-, CAIX+ (box-like pattern), S100-
  4. SMA+, desmin+, ER+, PAX8-, CD34-, cathepsin K-
Board review style answer #2
D. SMA+, desmin+, ER+, PAX8-, CD34-, cathepsin K-. Renal leiomyomas are positive for smooth muscle markers (SMA, desmin, h-caldesmon, calponin), ER and PR. They are negative for cytokeratins, PAX8, CD117, CD34, melanocytic markers and cathepsin K.

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Reference: Leiomyoma
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