The article presents a case of an adolescent patient suffering from osteochondritis of the humeral capitellum. Early symptoms of this disease appeared at an age typically associated with the onset of both Panner's disease and Osteochondritis Dissecans (OCD) of the humeral capitellum. About two years after the onset of the early symptoms, the patient reported to a specialised clinic. He was followed up for almost two years and was hospitalised and underwent surgical treatment during that period. Both diseases bear multiple similarities, which may entail diagnostic errors. The paper presents differences between these two similar clinical entities, in particular in terms of treatment and prognosis. Essential details potentially allowing for early diagnosis and classification of both conditions are described and discussed. Resolving the discussion may significantly contribute to improving performance and quality of life of patients suffering from necrosis of the humeral capitellum.