Microscopic description:

Under light microscopy, the distal portion of the ureter was filled with amorphous eosinophilic extracellular material. The amorphous material formed lobular masses mimicking malignancy. The eosinophilic and invariably homogenous proteinaceous martial expanded lamina propria and muscularis propria extending to the adventitia. Osseous metaplasia was apparent. The Congo red stain was positive which delineated a unique apple-green birefringence on polarization.

Discussion:

Primary localized amyloidosis of the ureter is a rare disease that is clinically and radiographically difficult to distinguish from urothelial carcinoma . Localized amyloidosis in the urinary tract is rare and could present as an incidental finding . It occurs predominantly in females, with a female to male ratio of 1.9:1 . The mean age at diagnosis is 58 years and most patients present with flank pain or hematuria.  The majority of  ureteric involvement (up to 60% of cases ) was reported in the lower ureter, followed by the upper portion according to a report by Ding et al. Primary localized amyloidosis of the urinary tract is most reported in the bladder . Till November 2013, we searched MEDLINE database for English articles using the key words “ureter amyloidosis” to select papers. Based on English articles or English abstract, 45 papers were found, and 49 cases of ureteral amyloidosis were identified. Lehmann reported the first case of localized amyloidosis of ureter in 1937.

Localized amyloidosis of the ureter is a benign, self-limited disease process that can easily be confused with a neoplastic process. Primary amyloidosis of the ureter with osseous metaplasia is a rare condition. Micro trauma or ischemia are the two insults which can result in osseous metaplasia formation. Microscopic finding could reveal pale pink, extracellular, glassy, hyaline material on hematoxylin eosin staining, most deposited in the vascular and perivascular areas. Additional confirmatory testing with Congo-Red staining is generally recommended for confirming the diagnosis. A study performed on patients with localized amyloidosis of the upper urinary tract showed no progressive disease process or recurrence during follow-up . Long term prognosis is excellent but other causes of amyloidosis should be ruled out to include testing for multiple myeloma with light chain studies.

References:

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Isaacson AL, Dahmoush L, Robinson RA. Primary localized amyloidosis presenting as urethral stricture: An important differential diagnosis on frozen section. Hum Pathol Case Rep. 2020;20:200365. doi:10.1016/j.ehpc.2020.200365

Ding X, Yan X, Ma X, et al. Localized amyloidosis of the ureter: A case report and literature review. Can Urol Assoc J J Assoc Urol Can. 2013;7(11-12):E764-767. doi:10.5489/cuaj.576

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Yalowitz PA, Kelalis PP. Primary Amyloidosis of the Ureter: Report of Case. J Urol. 1966;96(5):668-670. doi:10.1016/S0022-5347(17)63326-3

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Gertz MA, Dispenzieri A. Systemic Amyloidosis Recognition, Prognosis, and Therapy: A Systematic Review. JAMA. 2020;324(1):79-89. doi:10.1001/jama.2020.5493

Nobata H, Suga N, Itoh A, et al. Systemic AA amyloidosis in a patient with lung metastasis from renal cell carcinoma. Amyloid Int J Exp Clin Investig Off J Int Soc Amyloidosis. 2012;19(4):197-200. doi:10.3109/13506129.2012.712926

Borza T, Shah RB, Faerber GJ, Wolf JS. Localized amyloidosis of the upper urinary tract: a case series of three patients managed with reconstructive surgery or surveillance. J Endourol. 2010;24(4):641-644. doi:10.1089/end.2009.0383

CASE IMAGES