Adult Langerhans cell histiocytosis presenting as metachronous colonic polyps.

Langerhans cell histiocytosis (LCH) is a rare disease characterized by proliferation of Langerhans-type cells that express CD1a, Langerin (CD207) and S100 protein. Birbeck granules are a hallmark by ultrastructural examination. LCH presents with a wide clinical spectrum, ranging from solitary lesions of a single site (usually bone or skin) to multiple or disseminated multisystemic lesions, which can lead to severe organ dysfunction. Most cases occur in children. Gastrointestinal tract involvement is rare and has been associated with systemic illness and poor prognosis especially in children under the age of 2 years. Adult gastrointestinal LCH is very rare. We report a case of a previously healthy, nonsmoking 48-year-old male who was referred for routine screening colonoscopy. Two sessile, smooth, firm and yellowish LCH polyps measuring 0.2 cm and 0.3 cm were detected in the sigmoid colon. Fifteen months later a second colonoscopy found two histologically confirmed hyperplastic polyps at the sigmoid colon. No other LCH lesions were seen. A third colonoscopy after 28 months of follow-up found a submucosal 0.5 cm infiltrated and ulcerated LCH polyp in the cecum, close to the ostium of the appendix. The patient had been asymptomatic for all this period. Imaging investigation for systemic or multiorgan disease did not find any sign of extracolonic involvement. On histology all lesions showed typical LCH features and immunohistochemical analysis showed strong and diffuse staining for CD1a and CD207. This case illustrates two distinct clinicopathologic features not previously reported in this particular clinical setting: metachronous colonic involvement and positivity for CD207.