Primary Cutaneous Amyloidosis: A Clinical, Histopathological and Immunofluorescence Study

Introduction: Primary Localized Cutaneous Amyloidosis (PLCA) is a relatively rare chronic condition characterized by amyloid deposition in dermis without associated deposits in internal organs. Histopathology of cutaneous amyloidosis using Haematoxylin and Eosin (H&E) stain shows eosinophilic hyaline material in papillary dermis, which can be further confirmed by Congo Red (CR) staining or Direct Immunofluorescence (DIF) Test or immunohistochemistry.

Aim: To assess the concordance between the clinical, histo pathological and DIF findings in various subtypes of (PLCA).

Materials And Methods: Data was collected from patients attending the Outpatient Department (OPD) at a tertiary care centre in Karnataka, India, over a period of one and half years. A total of 50 patients with clinical features suggestive of cutaneous amyloidosis were subjected to histopathological examination with H&E, CR stain and immunofluorescence.

Results: Among 50 clinically suspected patients, the most common subtype was macular amyloidosis (70%) and lichen amyloidosis seen only in 16%. A biphasic pattern comprising of both macular and lichen amyloidosis was seen in 14% cases. Extensor aspect of the arm was the most frequently (76%) involved area. All the cases had multiple site involvement. Immunofluorescence positivity was 88% as compared to 86% on histopathology using CR stain. Amyloid deposits were detected in 80% of clinically diagnosed macular amyloidosis cases by histopathology using CR stain and in 85.7% by DIF, whereas in 5.7% cases, it was not detectable by both CR stain and DIF. Both immunofluorescence and CR staining were able to detect amyloid in all the cases of lichen amyloidosis. In biphasic amyloidosis, amyloid was detected in 100% cases on histopathology versus 85.7% cases on immunofluorescence.

Conclusion: CR stain and DIF are complimentary to each other for detection of macular amyloidosis. In case of lichen and biphasic amyloidosis, both CR and DIF are comparable modalities.