A repeated bone marrow biopsy presented 100% cellularity, marrow elements mostly composed of
histiocytes and markedly decreased marrow elements.
(14) CD68 is considered positive when diffuse granular cytoplasmic staining is present, but is not specific to
histiocytes. Lysozyme should show a cytoplasmic and/or Golgi/paranuclear pattern of staining.
These findings challenge the currently accepted diagnostic criteria for Sweet's Syndrome based on the predominance of
histiocytes and lymphocytes over neutrophils.
Emperipolesis related to RDD refers to the presence of
histiocytes containing intact lymphocytes within their cytoplasm.
Morphologically, the tumour pattern, as seen in other subtypes, is composed of a mixture of fibroblasts,
histiocytes and osteoclast-type giant cells in relatively changing amounts.
(5) The detection of clonal
histiocytes in all forms of LCH has been used as evidence that this disease is a clonal neoplastic disorder.
The patient was diagnosed as secondary HLH after an increased number of
histiocytes with hemophagocytosis were noticed in the bone marrow aspiration, supported by decreased fibrinogen and increased ferritin, which until the HLH diagnosis were thought to be due to numerous transfusions.
Among the 117 children with PLCH, four patients gave up treatment and lost to follow-up in the early stage of chemotherapy due to economic reasons, while the remaining 113 patients were treated according to
Histiocyte Society LCH-III protocol.
Caption: Figure 1: (a) Coronal MRI demonstrating a Tl-hypointense lesion in the right proximal tibia with cortical destruction; (b) hematoxylin and eosin- (H&E-) stained section of the patient's tibia lesion demonstrating numerous eosinophilic
histiocytes and emperipolesis (black circles).
Emperipolesis is the phagocytosis of cells such as lymphocytes and erythrocytes within another cell such as a
histiocyte. This is a characteristic of Rosai-Dorfman disease and was evident on histopathology of the tissue biopsy.
Immunohistochemical studies showed diffuse staining of the
histiocytes for S100 protein and CD68.
Histiocytic sarcomas are malignant proliferation of cells showing morphological and immunophenotypic characteristics of mature tissue
histiocytes [1, 2].