Acral keratosis with eosinophilic dermal deposits: a distinctive clinicopatholgic entity or colloid milium redux?

AIMS: The differential diagnosis of acral keratoses is broad. Encompassing a variety of infectious, heritable and degenerative disorders, emphasis upon the clinical setting and histologic subtlety are often required to arrive at the correct diagnosis. Herein, we report on a series of adult patients who presented with agminated or solitary papules of the distal finger found on histologic examination to contain amorphous eosinophilic deposits. RESULTS: The eosinophilic deposits were found in close proximity to the overlying epithelium and devoid of apoptotic keratinocytes, plasma cells, or vascular thickening reminiscent of amyloidosis or hyalinosis cutis. Special and immunostains yielded eosinophilic material that was elastin and Protein P negative. Despite a similar histomorphologic appearance to colloid milium, typical clinical features of this entity were not present. CONCLUSION: The etiologic significance of this condition is unknown. Potential sources of the material and a discussion of the differential diagnosis follow.