Pulmonary actinomycosis mimicking lung cancer on 18F-fluorodeoxyglucose positron emission tomography: a case report.

BACKGROUND: Pulmonary actinomycosis is a chronic disease characterized by abscess formation, draining sinuses, fistulae, and tissue fibrosis. It can mimic other conditions, particularly malignant and granulomatous diseases, and is perhaps extremely challenging to diagnose. CASE PRESENTATION: A 64-year-old Japanese man presented with 6-week history of a painful solid lump in the chest wall. Chest computed tomography scan revealed a mass-like consolidation in the left upper lobe, with rib erosion and direct extension into the anterior chest wall. 18F-fluorodeoxyglucose positron emission tomography scan showed increased metabolic activity in the mass, which is indicative of primary lung cancer. The bronchoscopy and computed tomography scan-guided transthoracic biopsy results were considered nondiagnostic. Finally, the patient was diagnosed with pulmonary actinomycosis via surgical resection. He completed an 8-week course of antibiotic therapy and experienced no recurrence. CONCLUSIONS: There is no difference in positron emission tomography/computed tomography scan findings between actinomycosis and malignancy. Therefore, pulmonary actinomycosis should be considered in the differential diagnosis of cases involving intensive activity on 18F-fluorodeoxyglucose positron emission tomography scan.

An EGFR T790M-mutated lung adenocarcinoma undergoing large-cell neuroendocrine carcinoma transformation after osimertinib therapy: a case report.

BACKGROUND: Osimertinib, a third-generation epidermal growth factor receptor tyrosine kinase inhibitor, is selective for both epidermal growth factor receptor tyrosine kinase inhibitor-sensitizing and T790M resistance mutations. Almost all patients who initially respond to an epidermal growth factor receptor tyrosine kinase inhibitor subsequently report disease progression. Epidermal growth factor receptor-dependent resistance mechanisms, bypass pathway activation, and histological transformation have been reported with osimertinib therapy. CASE PRESENTATION: We report a case of a 64-year-old Asian man with epidermal growth factor receptor T790M-positive adenocarcinoma that transformed to epidermal growth factor receptor T790M-negative large-cell neuroendocrine carcinoma after osimertinib therapy. A prompt rebiopsy revealed a rare mechanism of resistance to epidermal growth factor receptor tyrosine kinase inhibitor, and subsequently treatment with carboplatin and etoposide was effective. CONCLUSIONS: Despite the promising emergence of circulating tumoral DNA testing, this case report emphasizes the importance of rebiopsy of a progressive epidermal growth factor receptor-mutant tumor.

Transudative chylothorax associated with alcoholic cirrhosis.

We present the case of a 53-year-old man with decompensated alcoholic cirrhosis who was referred for right pleural effusion. After investigation, the patient was ultimately diagnosed with cirrhotic chylothorax. Chylothorax is a rare manifestation of cirrhosis, which results from the trans-diaphragmatic passage of chylous ascites. While chylothorax generally results in an exudative pleural effusion, cirrhotic chylothorax is always a transudative effusion. Biochemical characteristics are useful for diagnosis, avoiding potentially harmful diagnostic and therapeutic procedures.

Birt-Hogg-Dubé syndrome in the elderly.

We present the case of a 73-year-old woman who developed pneumothorax for the first time that was a clinical clue to the diagnosis of Birt-Hogg-Dubé (BHD) syndrome. Although younger onset of pneumothorax is more common in BHD syndrome, the characteristic chest CT findings may contribute to the diagnosis of this disorder in spontaneous pneumothorax of the elderly.

IgA nephropathy with diffuse alveolar haemorrhage.

Immunoglobulin (Ig)A nephropathy is the most common cause of primary glomerulonephritis worldwide. While IgA nephropathy has been associated with a variety of other diseases, pulmonary complications are extremely rare. A 58-year-old man presented with a 2-week history of fever and exertional dyspnoea. A chest imaging revealed bilateral consolidation predominantly in upper lungs. Laboratory findings showed elevated serum creatinine with proteinuria and haematuria. Flexible bronchoscopy revealed diffuse alveolar haemorrhage, and IgA nephropathy was confirmed on a renal biopsy. He received prednisone with good effect. This case highlights the need to consider IgA nephropathy in the differential diagnosis of pulmonary renal syndrome.