We present a case of an undifferentiated subtype of non-keratinizing squamous cell carcinoma (NK-SCC) with sarcomatoid features in the nasopharynx in a 69-year-old man who was difficult to diagnose due to spindle-shaped malignant cells. He was admitted because of a right nasal obstruction and right headache, and imaging revealed a heterogeneously enhanced irregularly shaped mass at the nasopharynx. Histopathologically, the tumour was partially organised, and the tumour cells were epithelioid or spindle-shaped. Initially, we erroneously diagnosed the tumour as an angiosarcoma owing to its false-negative immunoreaction for cytokeratins and a mistaken interpretation for CD31. After in situ hybridization for Epstein-Barr virus was positive, a consultation and additional immunostaining (including re-staining for cytokeratin with varying dilutions) were performed, and the diagnosis was revised to NK-SCC with sarcomatoid features. We believe that sarcomatoid features may be observed in nasopharyngeal carcinoma and in this case, immunostaining using various epithelial markers is necessary and careful attention should be paid to the interpretation of immunostaining.
Progressively transformed germinal centers (PTGC) is a benign process characterised by a morphological variant of reactive follicular hyperplasia in lymph nodes. It was recently shown that some cases of PTGC are associated with IgG4-related disease (IgG4-RD) or increased IgG4 plasma cells. Five years ago, a 57-year-old woman presented with enlargement of multiple lymph nodes in the left parotid, submandibular, and neck areas, pathologically diagnosed as PTGC after excisional biopsy. Since then, she has experienced numbness in her extremities, especially the left shoulder and arm, pruritus on the left side of the face and intermittent facial palsy, for which she has been receiving regular symptomatic treatment. Recently the patient developed diabetes mellitus (approximately seven months ago). In routine follow-up scans, a mass was detected in left kidney and magnetic resonance imaging of the abdomen prior to surgery revealed a slightly enhanced bulky mass replacing the pancreatic tail and uncinate process. The mass in left kidney was diagnosed as clear cell renal cell carcinoma, and the pathological features of the pancreatic lesion were those of IgG4-related chronic fibrosing pancreatitis. Retrograde examination of the neck lymph node diagnosed as PTGC showed increased deposition of IgG4-positive plasma cells.