Background Renal medullary carcinoma is one of the rarest malignancies arising from the kidney. Despite various aggressive therapeutic regimens, mortality remains significantly high (95%) with a median overall survival of 5 months. Furthermore, the scarcity of this malignancy renders randomized clinical trials impossible. We examined the expression of programmed death ligand 1 (PD-L1) in two new renal medullary carcinoma cases, investigated their responses to the PD-L1 inhibitor nivolumab and explored the predictive role of the rate of PD-L1 expression in such response. Case presentation Two African-American patients (male and female) with sickle cell trait who presented to our center with hematuria and flank pain were diagnosed with metastatic renal medullary carcinoma. PD-L1 was expressed at rate of 25% and 60% in patient 1 and 2 respectively. Following nephrectomy, they were started on nivolumab. Patient 1 initially responded to the treatment with regression of metastatic lesions. However, following this early response, patient 1 who has been receiving nivolumab for more than 15 months, was noted to have a disease progression. Patient 2 had disease progression after 3 months of nivolumab therapy. Conclusions Although PD-L1 is expressed in these patients with renal medullary carcinoma, response to nivolumab was only observed in patient 1 whose tumor has the lowest rate of PD-L1 expression. This may suggest that in RMC, response to PD-L1 inhibition therapy may not correlate with the rate of PD-L1 expression.

Adrenal cortical carcinosarcomas are a rare and typically aggressive malignancy with few reported cases in medical literature. We present a case of a 78-year-old female who presented with complaints of fatigue and right shoulder pain. Imaging of the abdomen with computed tomography visualized a large mass in the right upper quadrant. The mass was radiologically described as a 22 × 17 × 13 cm heterogeneous mass with its epicenter in the area of the right adrenal gland, with medial and peripheral effacement of all structures in the right upper quadrant. Non-contrasted images demonstrated anterior mid-portion calcifications. The mass parasitized its blood supply from several surrounding structures, including the liver and right psoas muscle, and extensively invaded the psoas muscle. Resection of the mass was performed with pathology, which revealed a high mitotic index and nuclear atypia with two morphologically and immunophenotypically distinct components. One of these components stained positively for calretinin and inhibin, which is indicative of adrenal cortical carcinoma; the other exhibited strong expression of vimentin and desmin, which was concordant with sarcomatous change and confirmed the diagnosis of adrenal cortical carcinosarcoma. This unique histology with both carcinomatous and sarcomatous components presents a diagnostic challenge for clinicians. As such, adrenal carcinosarcomas should be kept on the differential when evaluating retroperitoneal masses. Additionally, this study includes a review of 34 previously reported cases of adrenal cortical carcinosarcomas along with a discussion about the future exploration of this pathology.