Sinus histiocytosis with massive lymphoadenopathy (Rosai-Dorfman disease). Clinico-pathological analysis of a paediatric case

Histochemical and immunohistochemical studies performed in only a few cases of sinus histiocytosis with massive lymphoadenopathy (SHML) indicated that SHML cells belong to the macrophage--histiocyte system, though their exact origin is still uncertain. We analyzed the morphological, antigenic and enzymatic characteristics of the histiocyte-like cells in one paediatric case of SHML (also named Rosai-Dorfman disease). The SHML cells expressed the S-100 protein, lectins concanavalin A, peanut agglutinin and monocyte-macrophage related antigens CD 11c, CD 14, CD 33, CD 68 and LN 5. Reactivity with other anti-macrophage antibodies (MAC387, lysozyme, alpha-1 anti-chymotrypsin) was variable. The CD1a antigen was present only in scattered cells, whereas HLA-DR and the HLA-DR associated invariant chain were absent. Cytochemistry demonstrated an intense activity of acid phosphatase and non specific esterase of SHML cells. A large amount of medium sized mononuclear cells were located in the sinuses and intersinusoidal tissue. Our findings suggest that SHML cells have intermediate features between phagocytes and Langerhans cells/interdigitating reticulum cells. The heterogeneity of marker expression on SHML cells might be related to the local content of factors (e.g., cytokines), capable of modulating the phenotype of monocyted and derived cells

Rhabdomyosarcoma with primary osteolytic lesions simulating non-Hodgkin's lymphoma

We report the case of an 8-year-old child presenting with the pathological fracture of two vertebral bodies due to bone lytic lesions. Physical and instrumental examinations did not show any further evidence of disease. However, bone marrow aspirate showed an infiltrate of poorly differentiated cells. When the child was transferred to the Department of Pediatrics, lymphoblastic leukemia was suspected. Although the morphology of the bone marrow biopsy could have suggested a lymphoblastic lymphoma, further immunochemical and immunological studies together with the study of tissue surface antigens resulted in a diagnosis of embryonal rhabdomyosarcoma with an unusual presentation