A 27-year-old woman presents with a right neck enlargement of a lymph node. She states that lately she has been fatigued, with a feeling of malaise. The lymph node is removed, and a biopsy is obtained.
C. Langerhans cell histiocytosis (LCH)
Even though LCH has been reported to affect only lymph nodes, it is unusual and every effort should be made to make sure that other anatomical areas are not compromised. The histology in this lymph node is classic, since it shows a histiocytic proliferation with grooving of the nuclei, admixed with inflammatory cells including eosinophils. In the past, this entity was also know as histiocytosis X and eosinophilic granuloma. Currently, the most accepted terminology is LCH. However, it needs to be distinguished from other types of histiocytic disorders that may also affect lymph nodes, such as Rosai-Dorfman disease. By immunohistochemistry, LCH is positive for S-100 protein and CD1a, whereas other histiocytic types may show positive staining for S100 protein but negative staining for CD1a. The prognosis of patients with LCH depends of the involvement of other organs and the extent of the disease.