Microfilaria in lymph node mimicking Kimura disease
A 28-year-old male presented with a single, right, level 2 cervical lymph node of 2 months duration. No other relevant history was elicited. Routine blood test showed normal total leukocyte count, with 25% eosinophils in the differential count. The lymph node excision specimen measured 2 cm in diameter, with a grey-white cut surface. Initial microscopic sections showed lymph node tissue with intense eosinophil infiltration in the paracortical, medullary and germinal center areas with focal eosinophil microabscess formation. There was prominent follicular hyperplasia. No parasites were seen in the initial sections [].\nLymph node eosinophilia elicits many provisional diagnoses like Kimura disease, Hodgkin disease, hypereosinophilic syndrome/leukemia, angiolymphoid hyperplasia with eosinophilia, parasitic infection etc. Many causes of lymph node eosinophilia mentioned above were ruled out because of the absence of specific findings. Kimura disease could not be excluded. Almost all the findings like marked eosinophil infiltrate, eosinophil microabscess, follicular hyperplasia, fitted well for the diagnosis of Kimura disease, and the residents offered this as a provisional diagnosis. But, on keen observation of the initial sections, one finding did not fit into Kimura disease – the presence of focal foreign body giant cell reaction against a pale eosinophilic glassy/hyaline material [Figures and ].\nEven though eosinophilic material is described in Kimura disease, it is an amorphous type of eosinophilic proteinacious material[] without any giant cell reaction. The hyaline material led to the suspicion of a foreign body eliciting an eosinophil response and the patient being from a tropical country, the presence of a parasite was suspected.\nHence, the lymph node tissue was sectioned almost to the exhaustion of the wax block and a very careful search for an organism was made. In one or two serial sections, a few microfilariae were seen with a pale-staining ill-defined sheath and longitudinally arranged loose nuclei, the morphology suggesting microfilaria of filarial worm, possibly of Wuchereria bancrofti. The sheath is demarcated by adherence of inflammatory cells to its border, a finding also observed by Yenkeshwar et al, in their study.[] Thus, the thought about the possibility of a hidden parasite and the action of extensive sectioning and diligent search led to the correct diagnosis of the case [Figures –].