Angiomyeloproliferative lesions following autologous stem cell therapy

Abstract

Some reports suggest that autologous hematopoietic stem cell transplantation holds potential for treatment of renal diseases such as lupus nephritis, but the safety of delivering various stem cell types (hematopoietic, mesenchymal, and endothelial precursors) is not well established. Here, we report a case of lupus nephritis treated by direct renal injection of autologous stem cells recovered from peripheral blood. The patient developed masses at the sites of injection and hematuria. We suspected transitional cell carcinoma but nephrectomy revealed that the masses were angiomyeloproliferative lesions. We believe that this previously undescribed pathologic entity is stem cell-derived or -induced. The biologic potential, including the neoplastic potential, of this lesion is unknown. This case illustrates that the development of angiomyeloproliferative lesions is a possible complication of stem cell therapy.

Figure 1.

Macroscopic appearance of resected kidney. A solid hemorrhagic mass is present in the renal sinus, external to which is atrophic renal parenchyma. In addition, three similar smaller lesions are present (arrows), separate from the main lesion.

Figure 2.

Microscopic appearance of lesion. (A) The lesion is composed of numerous vascular channels, containing red cells and mixtures of hematopoietic cells. (B) The vascular component of the lesion consists of channels of varying caliber lined by benign-appearing endothelial cells. (C) and (D) The hematopoietic cells are mainly erythroid precursors with a smaller number of myeloid and megakaryocytic precursors mixed with numerous macrophages (larger foamy cells). (Hematoxylin and eosin; magnification: ×200 in A; ×600 in B through D.)

Figure 3.

Immunohistochemical profile of endothelial cells. Endothelial cells express (A) CD31, (B) VEGF receptor 1/Flt-1, and (C) VEGF receptor 2/Flk-1. (Immunoperoxidase; magnification: ×600 in A through C.)

Figure 4.

Immunohistochemical panel of hematopoietic cells. (A) There is widespread expression of CD44, marking the erythroid precursors but not megakaryocytic cells. (B) Virtually 100% of hematopoietic cells were cycling as demonstrated by MIB1 expression, whereas endothelial cells were not cycling. (C) CD68 staining highlights the large number of macrophages present both in vascular channels and in the intervening stroma. (Immunoperoxidase; magnification: ×600 in A and B; ×200 in C.)