Exceptional response to chemotherapy followed by concurrent radiotherapy and immunotherapy in a male with primary retroperitoneal serous Adenocarcinoma: a case report and literature review

Abstract

Background: Primary retroperitoneal serous adenocarcinoma (PRSA) is an extremely uncommon malignancy exclusively reported in females. Due to the rarity of the disease, it is difficult to establish a standardized treatment.

Case presentation: We describe a unique case of PRSA in a 71-year-old male who presented with right-sided lower back pain and numbness. Magnetic resonance imaging identified a mass invading the adjacent psoas muscle and twelfth rib. Tissue biopsy confirmed poorly differentiated PRSA. Patient was initially treated with neoadjuvant carboplatin and paclitaxel chemotherapy regimen. This resulted in complete radiological resolution of the tumor. However, 12 weeks later, rapid recurrence was noted on follow-up CT scan. The patient was then treated with external radiotherapy with concurrent nivolumab, an anti-PD-1 antibody. The patient displayed a positive response to treatment with reduction in primary tumor and metastases and had a sustained disease control.

Conclusion: Treatment with radiotherapy in combination with anti-PD-1 antibody could be an effective modality of management for PRSA.

Keywords: Chemotherapy; Nivolumab; PRSA; Primary retroperitoneal serous adenocarcinoma; Radiotherapy.

Fig. 1

Imaging studies demonstrating the course of tumor response to chemotherapy. a Retroperitoneal mass at time of diagnosis. b Reduction in tumor size after 12 weeks of therapy such that it is difficult to delineate from surrounding soft tissue. c Complete resolution of mass with minimal fat stranding d Recurrence of multinodular cystic mass at the site of origin. Circles highlight the location of the neoplasm

Fig. 2

Cytomorphology, histology and immunochemistry of primary peritoneal high grade serous carcinoma. a to c: Diff-Quick stain of touch preparation of cores, 20x, 60x and 60x, respectively; d and e: Hematoxylin and eosin stain of core biopsies, 10x and 400x, respectively; f to l: Immunohistochemical stains of the core biopsy. CK7 (1f), calretinin (1g), WT-1 (1h), p16 (1i), PAX-8 (1j), p53 (1 k) and ER (1l), 40x

Fig. 3

PET CT scan images showing changes in metabolic activity at the site of recurrent tumor after starting treatment with concurrent radiotherapy and immunotherapy. (a) and (c) illustrate a high standardized uptake values (SUV) in sagittal and axial sections respectively. It decreased in next 12 weeks following therapy as indicated by relatively decreased metabolic activity of tumor in sagittal (b) and axial sections (d)

Fig. 4

Changes in tumor burden under chemotherapy followed by radiotherapy and immunotherapy combination. RT: Radiotherapy, PDL1: programmed death ligand 1, CR: complete response, PR: partial response