Primary diaphragmatic inflammatory pseudotumour-like follicular/fibroblastic dendritic cell sarcoma mimicking a hepatic tumour: a case report.

An inflammatory pseudotumour-like follicular/fibroblastic dendritic cell sarcoma (IPT-like FDCS) is a rare Epstein-Barr virus-associated neoplasm that typically arises in the liver or spleen. We present a case of primary diaphragmatic IPT-like FDCS in a woman in her 70s who was incidentally found to have a subdiaphragmatic mass during routine follow-up. Preoperative imaging suggested a hepatic tumor. However, laparoscopic exploration revealed that the lesion originated from the diaphragm. The tumour was completely resected with partial diaphragmatic excision, followed by primary closure. Histopathological examination demonstrated characteristic inflammatory features, and in situ hybridization revealed Epstein-Barr virus-encoded RNA, confirming the diagnosis of IPT-like FDCS. The patient had an uncomplicated postoperative recovery and remained free of disease recurrence at 30 months after surgery. This case underscores the need to include diaphragmatic tumors when evaluating atypical hepatic dome lesions that lack the characteristic imaging features of hepatic malignancy.