Two types of histiocytic syndromes in one infant.

Histiocytic syndromes in children are divided into 3 classes: (i) Langerhans-cell histiocytosis (LCH) or Histiocytosis-X (HX), (ii) Hemophagocytic syndromes—Familial erythrophagocytic lymphohistiocytosis (FEL) and infection-associated hemophagocytic syndrome (IAHS) due to viruses (VAHS), and occasionally bacterial, fungal or parasitic, and (iii) Malignant histiocytic disorders(l). The lesional histiocytic cell in LCH/H-X is a dendritic cell, in IAHS an ordinary histiocyte (macrophage) as in pulmonary alveoli or Kupffer cells in the liver. Both cells arise from the mono-histiocytic lineage in the bone marrow and enter circulation till they reach tissues(2). We saw an interesting case in an infant who had both H-X and in IAHS.