Deep benign fibrous histiocytoma occurring in the kidney: Case report

RATIONALE: Deep benign fibrous histiocytoma (BFH) is relatively rare in contrast to superficial BFH involving the skin. Moreover, it was extremely rare for deep BFH occurring in the solid organ. To our knowledge, so far, only one case of deep BFH of the kidney was reported in English literature. PATIENT CONCERNS: Herein, we report another case of deep BFH located in the kidney in a 88-year-old female. She was referred to our hospital for a severe pain in the right upper abdomen. Computed tomography revealed a round low-density shadow measuring 6 cm in the kidney. DIAGNOSIS: The lesion was diagnosed as a deep BFH of the kidney, as the tumor was histologically predominately composed of bland ovoid cells arranged in a storiform pattern. INTERVENTION: The patient underwent the total resection of the right kidney with the tumor in our hospital. OUTCOMES: The postoperative course was uneventful. The patient was alive with no tumor recurrence or metastasis within 6 months of follow-up. LESSONS: We present another case of deep BFH of the kidney. Because of the rarity, the tumor may be poorly recognized. The typical storiform pattern in histology may be helpful for diagnosis. This report serves to remind that deep BFH is also a differential diagnosis for a tumor with storiform pattern in the kidney.