Localised renal Langerhans cell histiocytosis coexisting with unilateral renal clear cell carcinoma

Langerhans cell histiocytosis (LCH) is an uncommon group of disorders, which can be either localised or systemic, characterised by abnormal proliferation of monocytes, macrophages and dendritic cells. These disorders represent an aberrant response of myeloid progenitor cells. Bones are the most commonly affected organ but there can be involvement of the skin, lungs, liver and spleen. Renal involvement, however, is rare. LCH is the most commonly seen in children but certain rare forms such as Erdheim-Chester disease can be seen in adults. In this report, we present a case of clear cell renal adenocarcinoma (CCRC) admixed with LCH in a patient with history of smoking and presenting with abdominal pain and heamaturia. Imaging revealed left renal lesion and subsequently left renal nephrectomy was performed with tissue biopsy showing grade 3 clear cell renal cell carcinoma admixed with neoplastic LCH.