: ALK-positive histiocytosis is a rare malignancy which was first described in 2008 and recognized as systemic histiocytic disorder that can affect multiple organs. Less than 20 cases were reported to date, much fewer presented disseminated disease, especially with lung central nervous system (CNS) involvement. The clinical presentation, cytologic histologic features diverse prior cases. Diagno...

The cytotoxic interaction between cloned human Natural Killer (NK) cells and K562 target cells was studied using confocal laser scanning microscopy (CLSM) and conventional fluorescence microscopy. We observed, using fixed as well as living cells, the occurrence of (pseudo) emperipolesis during the interaction. About 30% of conjugated NK cells penetrated, partly or completely, into the target ce...

Peripolesis is a phenomenon in which a lymphocyte attaches itself to another cell, usually a macrophage or veiled cell, and proceeds to circle around it. In emperipolesis, a related phenomenon, the lymphocyte invaginates the target cell so deeply that it appears to be intracytoplasmic. Lung cells in bronchoalveolar lavage fluids from 20 patients were observed in the living state and filmed. Per...

Intracranial Rosai-Dorfman disease without systemic involvement is extremely rare. A 59-year-old woman presented with headaches. Magnetic resonance imaging revealed an enhancing posterior fossa convexity lesion with the dural tail sign. The preoperative diagnosis was meningioma. The histopathological examination revealed reactivity for S-100 and CD68 and non-reactivity for CD1a with emperipoles...

BACKGROUND Rosai-Dorfman disease (RDD) is a rare benign idiopathic histiocytic proliferation. Most commonly reported cases are lymph nodal. Only 30-40% of cases occur in extranodal sites. Although the morphological features of RDD are well documented, there is limited information about the morphometric variations in the histiocytes of this entity. METHOD Twenty-two cases of RDD diagnosed on f...

Rosai-Dorfman disease (RDD), also known as sinus histiocytosis with massive lymphadenopathy, is a rare disease of unknown etiology that typically presents as nodal disease in young children. However, it also can present in various extranodal sites and can be difficult to recognize if not considered in the differential diagnosis. Here, we report a case of appendix involvement by extranodal RDD, ...

BACKGROUND Hemophagocytic lymphohistiocytosis (HLH) is a clinical syndrome with both genetic and acquired causes characterized by elevated cytokine levels, hyperinflammation, and overactivation of lymphocytes and macrophages. It is typically a systemic disease with variable degrees of CNS involvement. Cases with predominantly central nervous system (CNS) involvement are very rare, with the vast...

Follicular dendritic cells (FDC) are unique nonlymphoid cells found only in germinal centers. FDC can be distinguished from other accessory cells based on a characteristic set of cell surface markers. It is known that FDC are able to rescue germinal center B cells from apoptosis. To investigate the role of FDC in the process of selection and maturation of B cells during germinal center reaction...

OBJECTIVE We describe a patient with seronegative autoimmune limbic encephalitis (SNALE) masquerading as glioma. Brain magnetic resonance imaging (MRI) abnormalities, distinctive pathological findings, and spontaneous remission are highlighted. BACKGROUND There are 15 previously reported SNALE cases, 1 with pathology. MATERIALS AND METHODS A 66-year-old man presented with prominent amnestic...

Recombinant human interleukin-6 (IL-6) has previously been shown to increase platelet counts in mice and primates. To elucidate the mechanisms underlying this phenomenon, serial analyses were performed on megakaryocytes obtained from rhesus monkeys treated for 8 days with 30 micrograms/kg/d of recombinant human IL-6. Platelet counts increased to a maximum of 7.8 x 10(5)/microL with biphasic pea...