AN 8-DAY-OLD male infant weighing 2892 g was referred to the hospital for evaluation of a chest wall mass. He had been delivered vaginally by vacuum extraction. The course of the pregnancy was unremarkable and the patient's mother received routine prenatal care.
On physical examination, the patient appeared well developed and was in no apparent distress. Vital signs were stable. A firm, immobile, nontender chest mass was located slightly to the left of the sternum. The mass measured 1.5 cm in diameter and projected 0.5 cm from the contour of the chest. Findings from the remainder of the examination were unremarkable.
Multiplanar imaging of the chest wall indicated a well-defined heterogeneous mass that appeared to grow from the intercostal muscles, invaded the intercostal muscles posteriorly, and displaced the pleura. The mass measured 1 × 2.5 × 2.5 cm in the anteroposterior, transverse, and cephalocaudal dimensions (Figure 1 and Figure 2). It did not involve the pericardium, but bony invasion of the ribs and sternum could not be completely excluded.
The next day, an incisional biopsy was performed. Histological study of the mass showed a predominant population of large polygonal cells and a smaller number of admixed multinucleate giant cells (Figure 3). Both the mononuclear and multinuclear cells had a moderate to large amount of lightly eosinophilic cytoplasm. The nuclei in the mononuclear and multinucleate cells were slightly enlarged and irregular, but significant hyperchromasia was not present and nucleoli were inconspicuous. The mitotic rate was low at fewer than 2 mitoses per 10 high-power fields. The lesion infiltrated skeletal muscle. Stains for fungi and mycobacteria were negative. The mononuclear and multinucleate cells were strongly positive on a vimentin stain. Actin, desmin, S100, factor VIII, and cytokeratin stains all were negative.
Thomas DB, Sidler AK, Huston BM. Radiological Case of the Month. Arch Pediatr Adolesc Med. 1998;152(10):1029-1030. doi:10.1001/archpedi.152.10.1029