Background Methotrexate (MTX) is a frequently used drug in the treatment of rheumatoid arthritis (RA), but occurrences of lymphoproliferative disorders (LPD) have been reported in patients undergoing an MTX regimen. Almost half of the patients with methotrexate-associated lymphoproliferative disorders (MTX-LPD) have extranodal lesions; moreover, although extremely rare, digestive tract perforations resulting from the extranodal lesions of MTX-LPD have also been reported. Case presentation We describe the case of an 81-year-old woman with RA who had been prescribed MTX at 6 mg per week for the past 11 years. She was admitted to our hospital with occasional abdominal pain and was first diagnosed with enteritis. Her abdominal pain did not improve, and a computed tomography scan showed abdominal effusion and free air in the abdominal cavity. She was diagnosed with a digestive tract perforation and underwent emergency surgery. The perforation site was identified in the jejunum, and she underwent small intestinal resection around the perforated region. The pathological findings showed an ulcer in the jejunum and infiltration of large atypical lymphocytes around the perforated region. An immunohistochemical examination revealed the expression of a cluster of differentiation 20 and latent membrane protein 1. Considering the patient’s history of RA treated with MTX, she was diagnosed as having Epstein–Barr virus (EBV)-related MTX-LPD with a histological diagnosis of EBVMCU. MTX was discontinued after the surgery, and her soluble interleukin-2 receptor (sIL-2R) levels had returned to normal 1 year later. She has had a good course for the 2 years since surgery and remains asymptomatic with no recurrence of MTX-LPD, as confirmed by the sIL-2R levels. Conclusion We experienced a rare case of the jejunum perforation induced by MTX-LPD. Since only a few cases have been reported of a patient with small intestinal perforation induced by MTX-LPD, further research is necessary to evaluate the clinicopathological features of MTX-LPD. The patient had disease remission after surgery and by discontinuing MTX treatment; our case did not require chemotherapy. EBV-positive patients, especially those with a pathological presentation of EBVMCU, could have a higher likelihood of remission, which could have been a factor in the present case.

Tuberculoma is a manifestation of pleural tuberculosis. Although the clinical manifestation of tuberculoma has been widely reported, the pathogenesis of this condition still remains unclear. An abnormal shadow was detected on the chest radiograph of a 44-year-old man with a history of pulmonary tuberculosis. Computed tomography revealed a well-defined, elliptical 44 mm nodule located in the right posterior thoracic cavity. Thoracoscopic surgery was performed to rule out malignant tumors. Although loose adhesions were observed throughout the thoracic cavity, a nodule was found between the visceral pleura and parietal pleura. En bloc resection was performed, and the patient was pathologically diagnosed with tuberculoma. An acid-fast bacterium culture was negative, and the patient’s recovery was uneventful without chemotherapy. Surgical resection should be considered to rule out malignancy, because tuberculomas are difficult to distinguish from malignant pleural tumors.

Glutathione S-transferase omega 2 (GSTO2) lacks any appreciable GST activity, but it exhibits thioltransferase activity. The significance of GSTO2 in lung function has been reported; however, the precise expression and molecular function of GSTO2 in the lungs remain unclear. In the present study, we found that GSTO2 is expressed in airway basal cells, non-ciliated, columnar Clara cells, and type II alveolar cells, which have self-renewal capacity in the lungs. Contrastingly, no GSTO2 expression was observed in 94 lung squamous cell carcinoma (LSCC) samples. When human LSCC cell lines were treated with 5-aza-2′-deoxycytidine, a DNA-methyltransferase inhibitor, GSTO2 transcription was induced, suggesting that aberrant GSTO2 hypermethylation in LSCC is the cause of its downregulation. Forced GSTO2 expression in How to cite this article: Sumiya R, Terayama M, Hagiwara T, et al. Loss of GSTO2 contributes to cell growth and mitochondria function via the p38 signaling in lung squamous cell carcinoma.

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