Synchronous and Metachronous Thyroid Cancer in Relation to Langerhans Cell Histiocytosis; Involvement of V600E BRAF-Mutation?

Langerhans cell histiocytosis (LCH) (cells identified in 1868, disease named in 1985), has a wide range of clinical presentations, including the rare event of infiltration of the thyroid gland. However, an association seems to exist between LCH and papillary thyroid carcinoma (PTC), as eight cases of LCH co-existing with PTC have been described in the english literature [1]. We extend this association with a metachronous case of PTC, occurring 4 years from the diagnosis of LCH, while the LCH was in remission (Table I). In our case PTCwas metachronous and not therapy related. This is verified by the fact that the patient did not receive etoposide or high doses of methotrexate, or local radiotherapy [2,3]. The radiation exposure was minimal; only two X-rays were performed at diagnosis, while imaging of the head was performed with MRI and no CT-scans. Therefore, a causative relationship is highly unlikely. More specifically, a 9-year-old boy, with low risk [RO-] LCH, V600E BRAF mutation positive, received vinblastine/ prednisolone according to the LCH III protocol, and achieved remission. Four years following diagnosis of LCH, in the routine