The patient was a previously healthy 73-year-old man who had been experiencing left chest pain for several days. The pain subsequently worsened, so he visited a primary care clinic and underwent chest radiography. It revealed left pleural effusion and a consolidation in the left upper lung. The patient was referred to our department for examination in September 2014. His occupation was in the manufacturing industry sector. He had a smoking history of 20 cigarettes per day for 40 years and was a moderate drinker. His oral hygiene was good and he was not in a state of immunodeficiency. He was taking medicine for dyslipidemia and esophageal reflux. The physical examination findings are described below. The principal vital signs were a heart rate of 103 beats/min, SpO2 of 92% and a body temperature of 35.6  C. A chest examination revealed decreased breath sounds at the left lower lung. Although the results of other systemic examinations were almost normal, we were able to confirm some of the radiological features. The results of a hemogram showed leukocytosis of 15.3 x 103/muL with left shift but the renal and liver parameters were normal. The C-reactive protein level was <0.02 mg/dl and the erythrocyte sedimentation rate was 2 mm per hour. The tumor markers, CEA and CYFRA, were negative. Sputum Gram stain was negative while sputum and blood cultures revealed no growth. The pleural effusion consisted of exudative fluid with prominent neutrophils and pH was decreased to 7.211. Glucose in the pleural effusion was 94 mg/dl and adenosine deaminase (ADA) was 25.1 U/L. Pleural effusion Gram stain and culture were negative. The patient was admitted with a diagnosis of complicated effusion and underwent chest tube insertion into the left thoracic cavity (Fig.1). Additionally, we administered 600 mg of clindamycin twice daily for 14 days. In spite of the treatment, the consolidation in the left upper lung remained. A chest CT scan confirmed the consolidation with an air bronchogram and a cavity in the left upper lobe. Flexible bronchoscopy was performed in order to make a diagnosis of the consolidation though nothing particular was noted during this procedure. Gram stain, Ziehl-Neelsen stain, polymerase chain reaction for Mycobacterium tuberculosis, and cultures for common bacteria, acid-fast bacilli, and fungi were all negative. A transbronchial lung biopsy (TBLB) was performed in apicoposterior segment of left upper lobe (B1/2) but we were unable make a diagnosis of the lesion. We planned a follow-up chest radiography examination and the patient was discharged from hospital.
Three months after discharge, the consolidation in the left upper lung had worsened (Fig.1)and we again tried to investigate its etiology. Physical examination findings were still normal. The previously existing consolidation in the left upper lung had worsened on chest CT, showing marked expansion in the left B1/2 (Fig.2), and the left plural effusion had decreased. Hemogram results were normal. The C-reactive protein level was <0.02 mg/dl and the erythrocyte sedimentation rate was 3 mm per hour. Aspergillus antigen and cryptococcal antigen were both negative and beta-D-glucan was 19.4 pg/ml. Flexible bronchoscopy was performed again. A Gram stain of bronchoalveolar lavage (BAL) showed profuse polymorphonuclear cells with a few GNR and GPR, and cultures grew Streptococcus constellatus/milleri. The biopsy specimen from the left B1/2 showed a mass of bacteria in the center with neutrophil infiltration, which was a round basophilic mass with a radiating arrangement of eosinophilic clubs on the surface (Fig.3). Grocott stain of the specimen showed filamentous bacteria. There was no malignancy in the specimen. Due to the characteristic findings of the pathological examination, the patient was eventually diagnosed with pulmonary actinomycosis.
Oral sultamicillin administration was initiated but this was changed to high-dose intravenous penicillin therapy, which was the usual method of treatment for actinomycosis, 35 days after starting antibiotics. Eighteen million units of penicillin per day were given for 4 weeks followed by oral therapy with amoxicillin. Four months after starting antibiotics, the consolidation in the left upper lung had improved without any side effects of amoxicillin. According to the conventional therapy, treatment with oral amoxicillin was continued for twelve months. His condition remained good on follow-up every 3 months.
Computed tomographic images with 1-mm collimation three months after discharge. The previously existing consolidation in the left upper lung has worsened, expanding particularly in apicoposterior segment of left upper lobe. A cavitary lesion has also developed.