Research Information System
REVISTA DA SOCIEDADE BRASILEIRA DE MEDICINA TROPICAL, vol.58, pp.1-2, 2025 (SCI-Expanded)
A 38-year-old woman presented with pain in her left shoulder upon palpation and during movement. Laboratory tests showed normal C-reactive protein (CRP) levels and sedimentation rates; however, ELISA results were suspiciously positive for hydatid cysts. Ultrasonography revealed a thick-walled, septate, anechoic cystic lesion. Contrast-enhanced shoulder magnetic resonance imaging revealed lesions extending from the humeral head to the elbow joint, causing proximal bone destruction and distal multilocular cystic lesions with internal septation within the bone marrow (Figures 1 and 2). Similar cystic lesions were found in the deltoid and supraspinatus muscles as well as in other muscle layers and subcutaneous tissue around the shoulder. Aspiration biopsy revealed acellular germinative membrane-like structures consistent with hydatid cysts. The patient was managed with aspiration and followed-up for 10 years, during which the lesion showed minimal progression but remained stable (Figure 3). At the most recent visit, the patient experienced recurring shoulder pain and movement restriction; the CRP level was elevated to 241 mg/L, while other laboratory parameters remained normal. Hydatid cysts primarily cycle between dogs and can infect humans through exposure to contaminated food and water1. They are found worldwide, particularly in the Mediterranean region. Musculoskeletal involvement is rare, accounting for 0.5-5% of cases and is almost always secondary to liver or lung infection2. Primary muscular hydatid cysts are uncommon and typically appear in peripheral muscles, such as the supraspinatus, biceps brachii, pectoralis major, gracilis, psoas, sartorius, and quadriceps. Few cases of hydatid cysts in the deltoid muscle have been reported in the literature3.