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.

Langerhans Cell Histiocytosis Associated With Renal Cell Carcinoma Is a Neoplastic Process: Clinicopathologic and Molecular Study of 7 Cases

Langerhans cell histiocytosis (LCH) is a rare histiocytic disorder composed of Langerhans cells admixed with reactive mononuclear and granulocytic cells, associated with prominent eosinophils. LCH is considered a neoplasm, driven in most cases by oncogenic RAS/RAF/MEK/ERK pathway mutations. The disease predominantly affects children. Urinary system involvement has rarely been reported in a multisystem disease setting. We describe 7 patients who presented with LCH occurring within (6 cases) or after (1 case) a resected clear cell (n=6) or clear cell papillary (n=1) renal cell carcinoma (RCC), identified prospectively in our routine and consultation files (2012 to 2019). The patients included 5 women and 2 men, with a median age of 54 years (range, 39 to 73 y), none with a history of LCH or LCH manifestations before the time of RCC diagnosis. The median size of the RCC was 3.5 cm (range, 1.8 to 8.3 cm). Treatment included partial (5 cases), or radical (2 cases) nephrectomy. All RCCs on gross examination showed at least focal cystic changes and were low grade (World Health Organization [WHO]/International Society of Urologic Pathologists [ISUP] grade 1 to 2). The LCH foci were detected as incidental histological finding within the resected RCC in all six cases and they were limited to few high-power fields (<2 mm) in 5 of 6 cases, but in the sixth case, they occupied almost the entire clear cell papillary RCC (2 cm nodule). No LCH manifestations were detected in the normal kidney or in perinephric fat. The seventh patient developed LCH within inguinal deep soft tissue followed by systemic manifestations 6 years after clear cell RCC. Langerhans cell immunophenotype was supported by the reactivity for S-100, CD1a, and langerin and by the negative pankeratin. Successful pyrosequencing of microdissected LCH DNA revealed the V600E BRAF mutation in all 6 cases of LCH within RCC. To our knowledge, only 3 similar cases were published since 1980; the only case tested for BRAF mutation showed wild-type BRAF. This is the first study analyzing the morphologic and genetic features of a cohort of LCH associated with RCC. In our experience, these cases may be underrecognized in practice, or may erroneously be diagnosed as RCC dedifferentiation or high-grade sarcomatoid transformation. Finally, the detection of BRAF mutation further confirms that LCH in this setting is indeed a neoplasm, rather than a reactive lesion.

Granulomata in Clear Cell Renal Cell Carcinoma: An Uncommon Presentation of a Common Cancer, Not Two Separate Entities

Sarcoidal-like granulomata (SLG) are known to occur as a response to a variety of tumor types, including lymphomas, prominently seminoma, other miscellaneous carcinomas, and rarely in renal cell carcinoma. There have been a handful of previously reported cases in the literature of SLG occurring in association with RCC. Of those previously reported, none were associated with infection and only 3 patients had a history of sarcoidosis. The prognostic significance of SLG in RCC is unsettled and somewhat complicated by the relative rarity of its occurrence and the paucity of data therein. A case is presented of an otherwise histologically typical clear cell renal cell carcinoma with peri-tumoral and intra-tumoral SLG. Special stains were negative for organisms and past medical history was negative for sarcoidosis and connective tissue disease.