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Extranodal marginal zone B‑cell lymphoma of mucosa‑associated lymphoid tissue (MALT lymphoma) occurring in inflammatory bowel diseases, including ulcerative colitis (UC) and Crohn's disease, has been reported, although it is extremely rare. An 18‑year‑old man with a two-years history of UC underwent colon endoscopy, and was found to have active total UC ranging from anus to cecum. Six biopsies were obtained. The microscopic examinations showed severe infiltrations of atypical small lymphocytes. They showed hyperchromatic nuclei and increased nucleocytoplasmic ratio and scattered immunoblastic cells. Centrocyte‑like atypical lymphocytes, monocytoid cells, and plasma cells were seen in some places. Vague germinal centers were present, and apparent lymphoepithelial lesions were seen. No crypt abscesses were seen, and there were few neutrophils. No apparent other findings of UC were seen. Immunohistochemically, the atypical lymphocytes were positive for vimentin, CD45, CD20, CD79α, CD138, κ‑chain, λ‑chain, and p53 and Ki‑67 antigen (labeling index = 63%). They were also positive for CD45RO, CD3, and CD15, but these positive cells were very scant compared with CD20 and CD79α. They were negative for CD10, CD30, CD56, cytokeratin (CK) AE1/3, CK CAM5.2, CK34BE12, CK5, CK6, CK7, CK8, CK14, CK18, CK19, CK20, EMA, chromogranin, synaptophysin, NSE, S100 protein, CEA, CA19‑9, p63, and HMB45. Without clinical information, the appearances are those of MALT lymphoma. However, with clinical information, making the diagnosis of MALT lymphoma was hesitated. It is only mentioned herein that atypical lymphocytic infiltrations indistinguishable from MALT lymphoma occurred in an 18‑year‑old male patient with a two-year history of UC. [ABSTRACT FROM AUTHOR]

Obvious neuroendocrine differentiation has not been reported in glomus tumor. The author herein reports a malignant glomus tumor of the foot showing obvious neuroendocrine differentiation. A 63-year-old woman presented with tumor of the left foot. The tumor was superficially seated, and located in the dermis. It was completely resected with wide margins. It measured 0.7 X 0.7 X 0.6 cm. Microscopically, the tumor was composed of atypical epithelioid cells located around blood vessel-like structures. The epithelioid cells showed relatively clear cytoplasm and severe cellular atypia, and resembled basal cell carcinoma. Focal areas of squamoid differentiation, carcinoid patterns, and neural differentiations were seen. There was no necrosis or atypical mitosis. However, mitotic figures were seen in 16 per 50 high-power-fields (HPF). The hematoxylin and eosin (HE) diagnosis was basosquamous carcinoma. Immunohistochemically, the tumor cells were strongly positive for vimentin, a-smooth muscle actin, and neuron-specific enolase. The tumor was focally positive for NCAM, synaptophysin and chromogranin. The blood vessel-like structures had a layer of CD31- and CD34-positive endothelial cells. Tp53 was positive and the Ki-67 labeling index was 23%. The tumor cells were negative for cytokeratin (CK) AE1/3, CK CAM5.2, CK5, CK6, CK7, CK8, CK14, CK18, CK19, CK20, p63, EMA, CEA, CA19-9, desmin, myoglobin, HMB-45, Melan-A, S100 protein, MUC1, MUC2, MUC5AC, and MUC6. Taken together with HE histology, the tumor was labeled as malignant glomus tumor with neuronal differentiation, based on the classification system of Folpe et al. The post-pathological diagnosis whole body examination using CT, MRI, PET, and endoscopies identified no tumors. The patient is now free from tumor and healthy 18 months after the resection. [ABSTRACT FROM AUTHOR]

Herein reported is a case of inflammatory pseudotumor (IPT) of kidney. It is not described in WHO, AFIP, and other books. A review of the literature revealed about 35 cases. A 76-year-old man underwent nephrectomy under clinical diagnosis of renal pelvic carcinoma. Grossly, a solid tumor was seen in renal parenchyma. Microscopically, it was composed of spindle cell tissue with inflammation and many necrotizing granulomas. Epithelioid histiocytes were abundant but giant cells were few. Lymphocytes and plasma cells were also seen. The features suggested tuberculosis (TB), but Ziehl-Neelsen stains and PCR revealed no TB bacillus. Immunohistochemistry showed that the tumor spindle cells were positive for vimentin, CD68, CD45, and Ki-67 (labeling = 18%), α-smooth muscle antigen, and NSE. Focal staining of KIT (mast cells), S100 protein (Langerhans cells), and CD10 (spindle cells) was present. IgG4 was negative. The tumor spindle cells were negative for other antigens examined. [ABSTRACT FROM AUTHOR]

Abstract  The author reports herein an extremely rare case of primary small cell carcinoma of the mediastinum with an emphasis on KIT and PDGFRA genes. A 66-year-old man was found to have a mediastinal tumor on a routine chest X-ray examination, and was admitted to our hospital. Imaging modalities revealed a 5 × 4 cm tumor in the middle mediastinum near the bronchial carina. No other tumors were detected in the body including the lungs. Video-assisted thoracoscopy confirmed the mediastinal tumor, and a large incisional biopsy was performed. The tumor was histologically small cell carcinoma. An immunohistochemical study revealed positive reactions for cytokeratins (AE1/3, polyclonal), synaptophysin, neuron-specific enolase, CD56, KIT, and PDGFRA, and negative reactions for chromogranin, CEA, CD45, CD20, and CD3. Ki-67 labeling showed a value of 80%. A molecular genetic analysis using PCR-direct sequencing identified no mutations of KIT (exons 9, 11, 13, and 17) and PDGFRA (exons 12 and 18) genes. The patient received radiation and chemotherapy, and the tumor was fully resolved. The patient has remained free of recurrence for 6 years after the first presentation. The present case is the first reported case of primary small cell carcinoma of the mediastinum with an examination of KIT and PDGFRA expressions and KIT and PDFGRA gene mutations. [ABSTRACT FROM AUTHOR]

Abstract  The author reports a rare case of primary large cystic extragastrointestinal stromal tumor (eGIST) of the transverse mesocolon with genetic analyses of the c-kit and platelet-derived growth factor receptor-α (PDGFRA) genes. A 78-year-old man was found to have a large cystic tumor in the abdomen, and the tumor was resected. Grossly, the tumor was located in the transverse mesocolon, and cystic. Microscopically, the tumor consisted of epithelioid cells with atypia. Mitotic figures were noted in five of 50 high power fields. Immunohistochemically, the tumor cells were positive for KIT, CD34, PDGFRA, and vimentin, but negative for cytokeratins, neuron specific enolase, desmin, S100 protein, α-smooth muscle actin, p53 protein, HMB45, CD68, CEA, factor VIII-related antigen, chromogranin, and synaptophysin. Ki67 labeling was 5%. Genetically, the tumor showed a point mutation (GAC → GTC) at codon 842 of exon 18 of the PDGFRA gene. Exon 12 of the PDGFRA gene and exons 9, 11, 13, and 17 of the c-kit gene showed no mutations. No recurrence is noted 3 years after the operation. This case shows that eGIST may occur in the transverse mesocolon. [ABSTRACT FROM AUTHOR]

Abstract  ‘Lymphomatosis cerebri’ (LC) is a term indicating a diffusely infiltrating form of primary central nervous system lymphoma (PCNSL) without evidence of a mass lesion. Not infrequently, diagnostic confusion is caused by its presentation on cranial magnetic resonance images (MRI), which is characterized by diffuse leukoencephalopathy without contrast enhancement. In this report, we describe a 53-year-old, immunocompetent man who had an insidiously progressive dementia and right weakness. On serial MRI in 4 months duration, diffuse white matter lesions without contrast enhancement gradually progressed, which was clinically consistent with his worsening condition. Biopsy specimen demonstrated nondestructive, diffusely infiltrating, large B-cell lymphoma, diagnosing LC. After the biopsy, corticosteroids were initiated, which dramatically alleviated his symptoms. Afterwards, he was treated by whole brain irradiation (total 36Gy) and discharged without noticeable deficits. Diagnosis of LC requires additional examinations generally not performed in the other white matter disorders. In suspected cases, biopsy should be performed to avoid deferring adequate cytostatic treatment. [ABSTRACT FROM AUTHOR]

Appendiceal diverticulosis is a rare condition. Herein reported is a case of appendiceal diverticulosis and diverticulitis clinically masquerading as appendiceal carcinoma. A 62-year-old woman presented with abdominal pain. US and CT showed a tumor measuring 5 x 4 x 4 cm in vermiform appendix. Colon endoscopy showed mucosal elevation and irregularity in the orifice of vermiform appendix. A biopsy of the appendiceal mucosa showed no significant changes. Clinical diagnosis was appendiceal carcinoma and wide excision of terminal ileum, appendix, cecum, and ascending colon was performed. Grossly, the appendix showed a tumor measuring 5 x 3 x 4 cm. The appendiceal lumen was opened, and the appendiceal mucosa was elevated and irregular. The periappendiceal tissue showed thickening. Microscopically, the lesion was multiple appendiceal diverticula. The diverticula were penetrating the muscle layer. The mucosa showed erosions in places. Much fibrosis, abscess formations, and lymphocytic infiltration were seen in the subserosa. Abscesses were also seen in the diverticular lumens. Some diverticula penetrated into the subserosa. The pathologic diagnosis was appendiceal diverticulitis. When they encounter an appendiceal mass, clinicians should consider appendiceal diverticulitis as a differential diagnosis. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented regarding the case of a 68-year-old Japanese woman diagnosed with sarcomatoid squamous cell carcinoma (SSCC) in the uterine cervix.