The patient was a 19-year-old male who was admitted with clinical manifestations consisting of intermittent localised pain in the left hemothorax accompanied by cough and febrile fever of one month's duration. In the general laboratory tests performed, the only notable findings were a leukocytosis of 16,500 x 109/l and an ESR of 24 mm in 1h, the rest of the complementary tests, including microbiological tests, were negative. The chest X-ray showed a mass with irregular borders that blurred the contour of the left pulmonary hilum. A chest CT scan confirmed the existence of a mass with sharper borders and hypodense areas in its interior located in the anterior mediastinum and in intimate contact with cardiac structures measuring 10 x 6 cm in diameter. The biopsy obtained by videothoracoscopy of the mass showed that it consisted of a proliferation of Langerhans cells with abundant eosinophils, histochemical stains showed positivity for S-100 and CD1a, being negative for lymphoid markers, all these findings were compatible with the diagnosis of LCH. After receiving 2 lines of chemotherapy treatment and without obtaining an evident response, it was necessary to initiate radiotherapy therapy, during which a lymphadenopathy appeared in the supraclavicular location, which after being biopsied showed evidence of nodular sclerosis-type Hodgkin's disease associated with LCH; after no response was observed to conventional treatment, autotransplantation of peripheral blood haematopoietic precursors was carried out, achieving complete remission of both diseases to date.