PMC4772676_01
Simple X-ray (a) and chest CT (b) showed a focal osteolytic lesion in the posterior arc of the left sixth rib. PET (c, d) revealed a solitary hypermetabolic lesion (SUVmax 7.1) at that site.
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F1
Radiography revealed a focal osteolytic lesion in the posterior arc of the left sixth rib (fig. 1a). Computed tomography (CT) of the chest showed an osteolytic lesion of about 1.6 x 1.1 cm in size with perilesional sclerotic change and inner cortical destruction at the posterior arc of the left sixth rib (fig. 1b). The maximum standardized uptake value (SUVmax) of the lesion at the left sixth rib was 7.1, suggesting malignancy (fig. 1c, d).
Histologic findings showed proliferation of histiocytes and eosinophil infiltration. Immunohistochemical stains were positive for S100 and CD1a, and negative for CD68.
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F2
Immunohistochemical stains were positive for S100 and CD1a (fig. 2), compatible with a diagnosis of LCH.