An 82-year- old man was referred to our hospital with a complaint of a bulge in the left chest wall. On palpation, the cystic mass was soft and highly flexible, without redness or heat. The patient had a history of left pleural effusion developed one year prior, and thoracoscopic examination had been performed because the adenosine deaminase (ADA) level in the pleural effusion was high (97.4 U/L). Malignant pleural diseases and tuberculous pleuritis had been ruled out by bacteriological and histological examination. Six months after thoracoscopy, computed tomography showed that the pleural effusion had decreased in volume, but there were numerous small nodular shadows in the left upper lobe; the nodules had increased in size and showed a tree in bud appearance, and a cystic mass appeared under the left scapula (Fig. 1). The patient had undergone surgery for lumbar spinal canal stenosis 13 years earlier, and needed a walking frame because of the complications of postoperative leg paresis. In addition, there was an episode of rehabilitation of shoulder movement performed three times a week for one year after the last thoracoscopic examination; treatment was discontinued due to shoulder pain.
Ultrasonography showed that the cystic mass had a wall of approximately 5 mm and contained numerous hyperechoic deposits (Fig. 2). Magnetic resonance imaging showed that the cystic mass was 12 cm in size and located inside the serratus anterior muscle below the scapula, and there were many crystalline structures inside the cystic mass that showed low signal intensity on T2-weighted images, suggesting scapulothoracic bursitis (Fig. 2). The white blood cell count and C-reactive protein levels were 5800/mul and 0.2 mg/dL, respectively. The erythrocyte sedimentation rate was 13 mm at 1 h, and T-SPOT. TB test was negative. Biochemical and microbiological examination of the cyst contents by needle aspiration and histological examination of the cyst wall by needle biopsy were performed to diagnose the cystic mass. The fluid in the cyst was orange and slightly turbid, and the ADA level in the cyst fluid was elevated (99.1. The results of the biochemical examination of the fluid contents are presented in Table 1. Mycobacterium tuberculosis was detected by a PCR test from the contents, and multinucleated giant cell infiltration was observed in the cyst wall.
Since there were no malignant findings, the patient was diagnosed with tuberculous scapulothoracic bursitis, and antituberculous therapy (rifampicin 450 mg, isoniazid 300 mg, ethambutol 750 mg) was initially started. However, imaging evaluation after 3 months of antituberculosis drug treatment showed enlargement of the cystic mass. Therefore, we decided to perform surgical excision.
The operative team donned N 95 masks, considering the rupture of the cystic mass. Under general anesthesia in the right lower decubitus position, a skin incision was made along the anterior border of the latissimus dorsi muscle from the axilla to the caudal margin of the mass. The serratus anterior muscle was split along the muscle bundle at the caudal side of the mass to reach the mass. In most places, the cystic mass was loosely adhered to the surrounding tissue, but part of the craniodorsal region was adhered to the fourth intercostal muscles, so the surface layer of the periosteum and intercostal muscle was resected. The cystic mass was resected without rupture (Video 1).
Supplementary video related to this article can be found at https://doi.org/10.1016/j.rmcr.2021.101537
The following is the supplementary data related to this article:
The cystic mass was composed of a uniformly fibrous wall containing numerous coin-shaped chondroid bodies (Fig. 3). Histological findings showed inflammatory cell infiltration, including lymphocytes, histiocytes, and plasma cells, inside the fibrous cyst wall. A granulomatous lesion with clusters of multinucleated giant cells, which was not accompanied by necrosis but suggested tuberculosis infection, was observed (Fig. 4).
As postoperative adjuvant therapy, the three antituberculosis drugs mentioned in section 2.3 were administered for 6 months. The chest wall cyst did not recur, the small nodular shadow in the left upper lobe improved, and exacerbation of tuberculosis was not observed for more than one year postoperatively.