Israel: A recent study in Acta Dermato-Venereologica has concluded that skin eosinophil counts in bullous pemphigoid patients are linked with worse treatment responses. However, skin eosinophil counts did not correlate with disease severity at the onset.
This retrospective study comprising 137 patients with bullous pemphigoid reviewed the pathology cases to determine the association of eosinophil counts with neurological comorbidities and treatment responses. It found that a high tissue eosinophil count was not linked with the worse disease at baseline but was associated with lower treatment response rates at the 1-, 3-, and 6-month follow-up. Tissue eosinophil counts were also linked with neurologic comorbidities.

Eosinophilic spongiosis and dermal infiltration of eosinophils are prominent features of bullous pemphigoid lesions. Although several observations have revealed the pathogenic role of eosinophils in bullous pemphigoid, few studies have examined the impact of skin eosinophil counts on treatment response and disease severity.
To fill the knowledge gap, Sharon Baum, Department of Dermatology, Sheba Medical Center, Tel HaShomer, Israel and colleagues examined the association between eosinophil counts in skin biopsy samples of 137 bullous pemphigoid patients and their comorbidities, demographic characteristics, treatment response, and disease severity in a retrospective study.
The study revealed the following findings:
There was no relationship between eosinophil count and age, sex, or disease severity at the onset.
There was a positive relationship between eosinophil counts and neurological comorbidity and a negative relationship between eosinophil counts and treatment response.
At all follow-up points, patients with no tissue eosinophils responded better to treatment than patients with any tissue eosinophil count.
The authors conclude, "skin eosinophil counts in bullous pemphigoid patients can serve as a negative prognostic marker for treatment response but are not correlated with disease severity at the onset."
About Bullous pemphigoid
Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease that typically occurs in the elderly. A generalized blistering and pruritic eruption characterize the disease; however, the clinical presentation can be polymorphic, particularly in the early pre-bullous phase.
Cutaneous infiltration by eosinophils is an important and early event in bullous lesions development in BP. The presence of degranulated eosinophils, extracellular eosinophil granules, and free granule proteins within the bullous lesions support Eosinophils' role in BP pathogenesis.
Reference:
Baum, S., Engler Markowitz, M., Lyakhovitsky, A., Gershon, R., Aviv, H., Segal, Z., & Barzilai, A. (2023). Skin Eosinophil Counts in Bullous Pemphigoid as a Prognostic Factor for Disease Severity and Treatment Response. Acta Dermato-Venereologica, 103, adv00850. https://doi.org/10.2340/actadv.v102.2938