Increased large unstained cells value in varicella patients: A valuable parameter to aid rapid diagnosis of varicella infection.

Varicella is a highly contagious infection caused by varicella zoster virus. Sometimes it is difficult to differentiate between other viral infections such as Kaposi's varicelliform eruption (KVE) and disseminated herpes zoster (HZ). The large unstained cells (LUC) value is a differential count parameter reported by routing hematology analysis. LUC have been studied previously, but never been reported in the context of varicella or in dermatological published work. The aim of this study was to compare the LUC values in varicella patients with that in KVE and disseminated HZ patients. Sixty-nine varicella patients, 30 KVE patients and 11 disseminated HZ patients were included in this retrospective study. All data were analyzed using SPSS version 17.0 or GraphPad Prism version 5.0. The mean percentage of LUC (%LUC) in varicella patients was higher than the upper limit of normal reference range and it was increased compared to %LUC of both KVE (P < 0.0001) and disseminated HZ (P = 0.0051) patients. %LUC of varicella patients significantly decreased with clinical improvements (P = 0.0017). %LUC was significantly increased in varicella patients and corresponded with clinical improvements. Patients with %LUC of 3.55 or more favor the diagnosis of varicella over both KVE and disseminated HZ with 71.01% sensitivity and 84.44% specificity. We suggest that %LUC can assist in making a precise diagnosis of varicella in confusing cases.