Langerhans’ cell histiocytosis mimicking relapse in a patient with follicular lymphoma

Abstract

Dear Editor, A 27-year-old man was admitted for evaluation of peripheral lymph nodes with no other systemic symptoms. Initial laboratory tests, peripheral blood smears and bone marrow examinations were unremarkable. The thoracoabdominal computed tomography (CT) scan showed thoracic lymph nodes and a bulky retroperitoneal adenopathic mass. After the lymph node biopsy, the patient was diagnosed with follicular lymphoma grade 3 (World Health Organization) stage 4-A, IPI 1/5, FLIPI 2/5. He received chemotherapy with CHOP–rituximab and local radiotherapy to the abdominal mass. The patient achieved criteria of complete remission uncertain (gallium scintigraphy negative), and he initiated maintenance therapy with rituximab. Three and a half years after, the patient noticed a progressive pain in the left area of the scalp, and he asked for evaluation. On physical examination, he presented a swelling on the left parieto-temporal area of the head that was painful at palpation. A cranial radiography showed an isolated radiolucent lesion on the left parietal zone of the skull. A cranial CT scan described a lytic lesion of 12 mm in diameter in the same area, with edema of subcutaneous tissue. Thoraco-abdominal CT scan and bone marrow biopsy were normal. Bone scintigraphy and 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) showed a locally increased uptake of 2×2 cm along the left parietal bone with extension to soft tissue. A surgical biopsy was decided, but a complete resection of the lesion was finally performed. The pathologic appearance of the lesion was a diffuse infiltration by cells with histiocytic appearance, vesicular nuclei, folded and grooved nuclear membranes, inconspicuous nucleoli, and abundant pale eosinophilic cytoplasm. This cluster of cells surrounded a large aggregation of eosinophils with central necrosis. Immunostaining showed cell positivity for CD1a and S-100 antibodies and negativity for CD79a, CD20, CD3, and CD5, and Ki67<5%, confirming the diagnosis of Langerhans’ cell histiocytosis (LCH). Six weeks later, FDG-PET was again performed, showing no abnormalities. No further treatment was administered. Two years later, the patient is in complete remission of either lymphoma or LCH. Histiocytic disorders represent a very heterogeneous and sometimes unclear group of diseases. The association with Hodgkin’s disease is well known, but association with other lymphoproliferative disorders is rare. To our knowledge, this is the second case of follicular lymphoma associated with LCH. In the first case, LCH was diagnosed simultaneously with the lymphoma. By contrast, in our case, LCH was diagnosed 3 years after the lymphoproliferative disease, when there was no evidence of follicular lymphoma progression. The origin of LCH is not clear, and there is Ann Hematol (2008) 87:675–676 DOI 10.1007/s00277-008-0459-y