Langerhans cell histiocytosis of the gingival mucosa with three recurrences over a 27 year period

Langerhans cell histiocytosis (LCH) is a group of rare and enigmatic disorders of the reticuloendothelial system characterised by abnormal, possibly neoplastic, proliferation of Langerhans cells. Oral lesions, in particular osteolytic lesions of the jaws, may be the primary or the sole manifestation of the disease. A 44 year old woman with a history of eosinophilic granuloma on the lower left canine region excised 25 years ago presented with an asymptomatic, ulcerated gingival lesion, extending lingual and distal to the right mandibular second premolar tooth, which was noticed approximately 6 months ago. The underlying bone was not involved. Histopathologic and immunohistochemical examination showed an LCH, consistent with eosinophilic granuloma. Radiotherapy was given, and 10 months later she developed three small painful ulcers located on the palatal gingivae around the right canine, between the second premolar and first molar, and around the right third molar, also diagnosed as eosinophilic granuloma. Eosinophilic granuloma may present in the gingival mucosa, in the absence of bone involvement, and may run a protracted course with remissions, reactivation and progression from single system to multi‐system involvement. Therefore, long‐term periodical follow‐up and restaging is mandatory. The presence of a high proportion of plasma cells expressing lambda‐light chains may cause a diagnostic dilemma with plasma cell malignancy would be interesting to be evaluated in additional cases.