An Extremely Rare Cause of an Obstructive Jaundice in Adults: Limited Langerhans Cell Histiocytosis of the Extrahepatic Bile Duct.

Langerhans cell histiocytosis (LCH) is a rare group of idiopathic disorders (previously termed "histiocytosis X") which is characterized by the presence of cells with characteristics similar to bone marrow-derived Langerhans cells which infiltrate various tissues and organs. Like Langerhans cells located in the skin, they express histiocytic markers such as S100, CD1a, and CD68 and contain Birbeck granules, which are rod-shaped intracytoplasmic organelles best demonstrated in electron microscopy. LCH primarily affects the skeleton, but lung, skin, liver, and lymph node involvement may occur alike. Hepatic involvement is well recognized in children, with sclerosing cholangitis occurring in 10-15% of those with multisystemic involvement, whereas LCH confined to the liver appears to be very unusual in adults. Up to date, only one case of a solitary LCH affliction of the extrahepatic bile duct lacking liver involvement in adulthood has been reported on in the literature. We here report on a 60-year-old male patient with classical indolent progressive obstructive jaundice. The diagnostic workup revealed a tumorous lesion in the middle third of the common hepatic bile duct, initially being highly suspicious of an extrahepatic cholangiocarcinoma. CT scans further suspected an infiltration of the right portal vein, implicating a potentially extensive tumor growth, but a preoperative histological confirmation was not feasible. The serum tumor marker CA19-9 was 48 U/mL. The patient then underwent an explorative laparotomy with a pylorus preserving pancreaticoduodenectomy, as all frozen section tissue specimens revealed no tumor infiltration. The final result of the histopathological examination revealed an isolated LCH in the extrahepatic bile duct with a consecutive secondary sclerosing cholangitis. To complete the tumor staging, a thorax CT scan was performed and a generalized histiocytosis was ruled out, hence confirming the localized character of the disease. To the best of our knowledge and after a comprehensive literature review, we report on the second case globally, which describes a primary LCH limited to the extrahepatic bile duct in adulthood. A generalized sclerosing cholangitis in the liver was ruled out by radiological imaging. Preoperative histological affirmation of such findings is very confined due to the complexity and hence can only be diagnosed in the postoperative specimen. However, patients with nondisseminated sole findings, usually report a good prognostic outcome after surgical resection despite the paucity of corresponding data.