Clinicopathological digital image analyses before and after thermal stimulation subdivide acquired idiopathic generalized anhidrosis into inflammatory and non-inflammatory type

Abstract

Background: Acquired idiopathic generalized anhidrosis (AIGA) manifests varying degrees of syringotropic inflammation.

Objective: To better understand the basis of inflammation in AIGA.

Methods: Changes in the extent of cell infiltration around the sweat gland/duct and the difference in the expression level of immune privilege (IP)-related/sweat gland markers before and after thermal stimulation were assessed in AIGA. We also adopted a semi-quantitative digital image analysis of sweating as detected by the starch-iodine method. The changes in sweating before and after treatment was defined as the improvement index.

Results: Nine AIGA cases were analyzed. Two cases with minimal inflammation were defined as non-inflammatory type (non-inf)AIGA, while others with evident cell infiltration were defined as inflammatory type (inf)AIGA. MHC class I was significantly upregulated with downregulation of macrophage migration inhibitory factor and alpha-melanocyte-stimulating hormone exclusively in the sweat duct of infAIGA after thermal stimulation (p < 0.05). Furthermore, the extent of inflammation and the ductal dermcidin expression prior to thermal stimulation were inversely correlated (r = - 0.807), while that and the ductal claudin-1 expression after thermal stimulation was positively correlated (r = 0.875). The improvement index positively correlated with the degree of inflammation after thermal stimulation implying possible contribution of inflammation in AIGA pathophysiology. In addition, interferon-induced protein 10 and claudin-1 expression level in the sweat duct before thermal stimulation respectively correlated with the improvement index (r = 0.750, and 0.762).

Conclusion: The pathophysiology of AIGA may be subcategorized into two groups: IP-collapse possibly play some roles in infAIGA, while ductal dysfunction may exist in non-infAIGA.

Keywords: Acquired idiopathic generalized anhidrosis; Digital image analysis; Immune privilege; Sweat gland; Thermal stimulation.