Editor: Mahmut Akgul (

2022-39/October 10

Contributors: Caroline Maltez, Leandro LL Freitas, Athanase Billis

A female in her 60s with an incidentally found kidney tumor. Partial nephrectomy was performed.



a) Glomus tumor

b) Myopericytoma

c) Myofibroma

d) Angioleiomyoma

e) Fat-poor angiomyolipoma

Renal angioleiomyoma

Glomus tumors and variants, myopericitoma (including myofibroma), and angioleiomyoma belong to a class of “pericytic (perivascular) tumors”. These tumors exhibit a pattern of differentiation related to the perivascular myoid cells that physiologically invest blood vessels and are morphologically related. This family of tumors occurs most characteristically in superficial soft tissues and distinctly infrequently in deep soft tissues or visceral sites.

Morphologically, our case is consistent with angioleiomyoma which has been observed in 3 single case reports presenting as renal masses or hemorrhage and 1 case in a series of 17 cases of pericytic tumors of the kidney (1-4). Macroscopically, the tumor was well delimited and measured 2.9×2.2×1.3 cm. Microscopically, showed prominent blood vessels with thick walls of mature smooth muscle cells (Figs. 1-3) which in many areas appear to blend into the adjacent edematous stroma (Fig. 4). The neoplastic cells are cytologically bland, the nuclei elongated and the cytoplasm eosinophilic. In areas of the periphery of the tumor, neoplastic cells formed thick bundles of smooth muscle cells establishing the external limit of the tumor (Figs. 1 and 2). No atypia, necrosis or mitotic figures were seen.

Immunohistochemically, the tumor was diffusely positive for 1A4 and caldesmon, focally for desmin, and positive for CD34 in the endothelial cells of the blood vessels (Fig. 5). It was negative for AE1/AE3, HMB-45, Melan-A, S100, HHV8, chromogranin and synaptophysin. Ki-67 was <1%.

Angiomyolipoma without adipose tissue is a differential diagnosis to be considered but HMB-45 and Melan-A were both negative. Furthermore, the blood vessels in angiomyolipoma characteristically may show fibrous and hyalinized walls. Glomus tumors consist of lobules of circumscribed monotonous-appearing round to oval cells with well-defined cell borders around variably sized blood vessels. Myopericytomas are characterized by spindle, round, or oval myoid cells around the vascular endothelium and are arranged in a striking concentric fashion. Myofibroma appears as histologic variant of myopericytoma. The presence of hybrid cases with overlapping morphologic and immunohistochemical features may be in favoring the existence of a continuous spectrum of perivascular myoid tumors (5-6). In spite of the rare occurrence of all these mesenchymal tumors in the kidney, the cumulative experience favors an indolent behavior.

1. Sirohi D, Smith SC, Epstein JI, Balzer BL, Simko J Balitzer D et al. Peicytic tumors of the kidney-a clinicopathologic analysis of 17 cases; Hum Pathol 2017;64:106-117.

2. Huang Y, Xiong Z. Angioleiomyoma of the kidney parenchyma. Indian J Pathol Microbiol 2013;56:318-9.

3. Kunimatsu N, Kunimatsu A, Kojima K, Hirabayasi Y, Ohtomo K. A case of renal angioleiomyoma with rapid growing: CT findings with histopathological correlation. Radiat Med 2004;22:437-41.

4. Vogel J, Harder T, Weissbach L. Aneurysmal hemorrhage of the kidney caused by angioleiomyoma. Eur Urol 1986;12:438-40

5. Matsuyama A, Hisaoka M, Hashimoto H. Angioleiomyoma: a clinicopathologic and immunohistochemical reappraisal with special reference to the correlation with myopericytoma. Hum Pathol 2007;38:645-51.

6. Zhao M, Williamson S, Sun K, Zhu Y, Li C, Xia W et al. Benign perivascular myoid cell tumor (myopericytoma) of the urinary tract: a report of 2 cases with an emphasis on differential diagnosis. Hum Pathol 2014;45:1115-21.

Caroline Maltez, Leandro LL Freitas, Athanase Billis
Department of Pathology, School of Medical Sciences
State University of Campinas (Unicamp)


Kidney; angioleiomyoma; myopericytoma; pericytic tumors