Eosinophilic globules in spindle cell and epithelioid cell nevi: composition and possible origin

The presence of eosinophilic globules has been described as a helpful sign for the histologic differentiation of Spitz's nevus from malignant melanoma. The origin of these bodies is not clear, and they have been likened to Civatte or colloid bodies of lichen planus. This would suggest that they might originate from degenerating keratinocytes or melanocytes or both. These eosinophilic globules and the colloid bodies of lichen planus have been reported to be similar in that they both stain positively for type IV collagen and laminin. These previous reports have failed to include, or have not emphasized, the staining for keratin that separates these two bodies. We stained 10 spindle cell and epithelial cell (S&E) nevi for S-100 protein, keratin, vimentin, type IV collagen, and laminin. In all 10 cases of S&E nevi, the eosinophilic globules showed a positive reaction for type IV collagen and laminin and a negative reaction for keratin, S100 protein, and vimentin, unlike the colloid bodies of lichen planus, which showed a negative reaction for type IV collagen and laminin and also a strong positive reaction for keratin. These results suggest that the eosinophilic globules of Spitz's nevi are basement membrane material, perhaps synthesized by either basal cells, melanocytes or both, and are not degenerated basal cells or melanocytes.