A 25-year-old Indian man presented with a swelling of 3-weeks duration over the anterior aspect of his left chest (Fig. 1). The swelling was painful and associated with intermittent low-grade fever. It was insidious in onset and gradually progressive in size. There was no history of cough, hemoptysis, recent weight loss, anorexia, pruritus, seizures, or similar swellings elsewhere in the body. The swelling was not associated with any preceding history of trauma. His medical and family histories were noncontributory. The patient had visited a primary care physician who made the provisional diagnosis of muscular cysticercosis and referred the patient to our institution. On examination, the patient's vital signs were stable and there was no evidence of lymphadenopathy. His physical status was good. Local examination revealed a tender 5-cm 9 3-cm hemispheric fluctuant mass located over the left lower chest wall anteriorly near midline. Its margins were not well defined. Local temperature was increased. The overlying skin was freely mobile and there were no scars or sinuses. On attempted contraction of the upper abdominal muscles, there was no change in the size of the swelling; however, its side-to-side mobility became restricted, suggestive of a swelling arising in the muscle. The rest of the organ systems (respiratory system, abdomen, nervous system) appeared normal on clinical examination.Laboratory examination revealed an increased leukocyte count (13,400/mm 3 ) and the differential count was 60 polymorphonuclear leukocytes, 35 lymphocytes, two monocytes, and three eosinophils. The erythrocyte sedimentation rate (53 mm at the end of the first hour) and C-reactive protein (10.3 mg/L) levels were increased. The sputum examination was negative for acid-fast bacilli. Enzyme-linked immunosorbant assay (ELISA) was negative for cysticercosis antibodies. The ELISA test for HIV I and II antibodies was negative. The patient's immune status was normal with no other focus of infection.The patient underwent imaging studies and laboratory tests. Plain radiographs of the chest were normal. Ultrasound, CT, and MRI of the chest were performed.Based on the history, physical examination, and imaging studies, what is the differential diagnosis?
Imaging InterpretationUltrasound examination revealed an oval hypoechoic lesion 5 cm 9 3 cm 9 2 cm in the substance of the left rectus abdominis muscle with increased echogenicity of adjacent muscle fibers suggestive of edema; however, there was no evidence of hyperechoic focus (suggestive of calcification or scolex) in the lesion. Doppler examination Each author certifies that he has no commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. Each author certifies that his institution approved the reporting of this case report, that all investigations were conducted in conformity with ethical principles of research, and that informed consent for participa...