Low-grade tracheal adenocarcinoma with ETV6::NTRK3 fusion: unique morphology akin to subsets of sinonasal low-grade non-intestinal-type adenocarcinoma.

The prevalence of NTRK fusions in non-small cell carcinoma (NSCLC) is only approximately 0.2%, most of which harbor NTRK1 fusions. NSCLCs with NTRK3 fusions are extremely rare. Herein, we report a case of low-grade tracheal adenocarcinoma in a 64-year-old woman. Histologically, areas of complicated tubule-papillary or cribriform patterns constituted a major component of the tumor and comprised cuboidal to columnar epithelial tumor cells with pale eosinophilic cytoplasm and cytoplasmic mucin, similar to subsets of sinonasal low-grade non-intestinal-type adenocarcinomas. Immunohistochemically, the tumor was positive for MUC5AC and MUC4 and showed nuclear expression of the pan-Trk antibody. ETV6::NTRK3 was identified by reverse transcription-polymerase chain reaction using formalin-fixed paraffin-embedded tissues. To the best of our knowledge, this is the first case of low-grade tracheal adenocarcinoma with ETV6::NTRK3 fusion. Our case illustrates that low-grade adenocarcinomas with ETV6::NTRK3 fusion may exist throughout the respiratory tract.

Adenosquamous carcinoma of the lung in a patient with complete situs inversus.

We present a rare case of adenosquamous carcinoma of the lung in a patient with complete situs inversus. The patient was a 76-year-old woman with the chief complaint of hemosputum. Chest X-ray and computed tomography (CT) scans of the thorax showed a mirror image of the organs and vessels and revealed a tumor 3.5 cm in diameter, in the left lower lung field. She was referred and admitted to KKR Hokuriku Hospital, Kanazawa, Japan to undergo surgery. Bronchoscopy showed a mirror image of the usual arrangement of the bronchi, and 5 segmental branches in the left lower bronchi. During surgery, care was exercised when intubation with the Univent bronchial tube for one-lung ventilation. On thoracotomy, the gross appearance of the left lung and the arrangement of the pulmonary vessels and the bronchi corresponded to those normally found on the right side. We were successful in performing a left lower lobectomy. Postoperative diagnosis confirmed an adenosquamous carcinoma with localized pleural dissemination as p-t4n1m0, stage IIIa. Preoperative imaging, including CT, bronchoscopy, and angiographic examination of the patient, will be useful for prevention of vascular or bronchial injury during surgery in patients with complete situs inversus undergoing lung resection. Possible vascular or bronchial anomalies should always be taken into consideration while operating on these patients.

Primary minute invasive de novo colonic adenocarcinoma appearing as submucosal tumor.

A 4 mm white-yellow submucosal tumor-like lesion was detected in the sigmoid colon of an asymptomatic 52-yr-old Japanese man. Because the lesion was unexpectedly suspicious for adenocarcinoma by pathological examination of the biopsy specimen, it was treated by endoscopic mucosal resection. The specimen obtained demonstrated well-differentiated adenocarcinoma without any adenomatous element, and was located principally in the submucosal layer with a maximum depth of 1600 mum from the muscularis mucosae. The cancer exposed to the luminal surface was pathologically concluded to be diminutive. Intriguingly, aggregation of lymphocytes was found beneath the mucosal layer, which might have compromised the integrity of the muscularis mucosae. Because of deep submucosal infiltration and the latent aggressive nature of de novo cancer, the patient underwent an additional partial sigmoidcolectomy, which demonstrated no residual cancer and no regional lymph node metastasis. The lesion in this patient exhibited a previously undescribed appearance of de novo colon cancer as submucosal tumor in an early phase of growth.

Small follicular lymphoma arising near the ampulla of vater: a distinct subtype of duodenal lymphoma?

A 49-yr-old Japanese woman underwent upper gastrointestinal endoscopy because of nonspecific dyspepsia. Endoscopy revealed a flat elevated lesion about 15 mm in diameter adjacent to the duodenal papilla, the surface of which was uneven and covered with whitish granules. Based on the results of histological examination with immunohistochemistry (positive for CD10, CD20, CD79a, and bcl-2 protein, negative for CD5 and cyclin D1), a diagnosis of grade 1/3 follicular lymphoma was established. Systemic staging examinations suggested the lymphoma was restricted to the mucosa and superficial portion of the submucosa in the duodenal wall. The patient was treated with a combination of CHOP chemotherapy (cyclophosphamide, doxorubicin, vincristine, and prednisolone) and monoclonal anti-CD20 antibody (rituximab), in addition to radiotherapy. After six courses of this combination chemotherapy, complete regression of the lymphoma was observed. Although reports of small duodenal lymphoma (<20 mm or localized to the mucosa or submucosa) are extremely rare, the features of this case are characteristic of small duodenal lymphoma in terms of evolution around the ampulla of Vater, low-grade follicular type, occurrence in a women, occurrence in the fourth decade of life, and favorable outcome, and this type of tumor may need to be distinguished by pathogenesis and clinical behavior from various other gastrointestinal lymphomas.