Eosinophilic Granuloma Showing Rapid Regression: Report of a Mandibular Case with Application of a Modified PNA Staining Method for Demonstration of Langerhans‐type Histiocytes

A mandibular eosinophilic granuloma in a 16-year-old male is reported. This case showed rapid regression, which was clearly demonstrated by histopathological examinations of both preoperative biopsy and surgical materials. Transformation from an eosinophilic granuloma to a xanthomatous granuloma with multinucleated giant cells was observed after only 26 days. Special staining of paraffin sections with peanut agglutinin (PNA) and use of electron microscopy showed that the main component of the lesion in the biopsy material was Langerhans-type histiocytes. These cells had disappeared from the lesion by the time of the operation. At the same time, the number of infiltrating eosinophils was also markedly reduced. It seems appropriate to consider that the rapid regression of this disease was correlated with the rapid reduction in the number of Langerhans-type histiocytes appearing in the granulomatous foci, as well as the number of infiltrating eosinophils.