Histologic changes: At low magnification (A), an early, cellular lesion occupies the peribronchiolar interstitium and adjacent alveoli. Although often stellate in shape, lesions may also be rounded, as is this one. Central cavitation, not associated with inflammation, develops (C). Note the arteries (arrows), which identify the location of the now-destroyed bronchovascular bundle.


At higher magnification (B), the cells have poorly-demarcated cytoplasmic boundaries. Nuclei have irregular shapes and indentations (arrow at bottom marks a good one). Scattered inflammatory cells include eosinophils and lymphocytes. In the context of the clinical history and radiographic findings, what is the diagnosis? Answer. What immunohistochemical test(s) can confirm the diagnosis? Answer


Clinical summary Image 2

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Answer: In a smoker with dyspnea, radiographic nodules with cavitation, and a histologic peribronchiolar interstitial lesion composed of cells with irregular, indented nuclei and inflammatory cells including eosinophils, the diagnosis is Langerhans' cell histiocytosis (LCH).
































Answer: Langerhans' cells react with antibody to CD1a (OKT6). They also react with antibody to S-100, but it is less specific, as other cells, including some macrophages, also react with it.