Hydroxyethyl starch-induced itch: relevance of light microscopic analysis of semi-thin sections and electron microscopy.

Background: Hydroxyethyl starch (HES) is widely used as a plasma substitute for improving microcirculation. A major side effect of HES is severe pruritus caused by HES deposits in the skin. Since specific changes are difficult to see in paraffin sections, electron microscopy is the golden standard technique in the diagnosis of HES-induced skin disease. Our aim was to compare electron microscopic search for HES deposits with other techniques.

Patients And Methods: During the last ten years, we biopsied 21 patients suspected of having HES-induced pruritus. We compared conventional microscopy with hematoxylin & eosin and toluidine blue-stained paraffin sections, toluidine blue-stained glycide ether-embedded, semithin sections and transmission electron microscopy.

Results: In 9 patients specific HES deposits could be found by evaluating toluidine blue stained semithin sections by light microscopy alone. In 6 of these cases electron microscopy was also done and confirmed the findings. In contrast, no specific findings due to HES deposits could be detected by conventional histology.

Conclusions: If specific HES deposits are found in toluidine blue-stained, glycide ether-embedded semithin sections, electron microscopy is not required.