Primary localized cutaneous amyloidosis – A clinicopathological study

摘要

Introduction: Cutaneous amyloidosis can be a manifestation of a systemic disorder or can result from localized process confined to the skin. Involvement of apparently normal skin is known as primary localized cutaneous amyloidosis. Histopathologically, amyloid appears as amorphous, eosinophilic material with hematoxylin and eosin stain. Congo red staining with apple-green birefringence under polarized microscopy confirms the diagnosis. Materials and Methods: Thirty-nine patients with a differential diagnosis of cutaneous amyloidosis reporting to the dermatology outpatient department of our hospital from November 2015 to May 2018 were studied. Twenty-six cases showed features of amyloidosis on histopathology. These were categorized into morphologic types of amyloidosis and correlated with the available clinical history. Congo red staining and observation under polarized microscope were done. Results: We encountered lichen and macular types of cutaneous amyloidosis with slight female predominance. Majority of the lesions were pruritic with involvement of the pretibial region. A history of friction was given by a few. All cases diagnosed clinically were concordant histopathologically. However, a single case of lichen amyloidosis was diagnosed solely based on histology. Microscopically, hyperkeratosis, amyloid deposits in the papillary dermis, and perivascular inflammation were the most consistent findings. All the cases showed apple-green birefringence with Congo red stain under polarized microscope. Conclusion: Cutaneous amyloidosis can have a wide range of differential diagnosis due to its varied clinical presentation. Histopathology, with the use of special stains, helps in identifying amyloid with a high degree of accuracy.