Primary localised cutaneous amyloidosis in Malaysians

Area of Science:

• Dermatology
• Pathology
• Immunohistochemistry

Background:

• Primary localized cutaneous amyloidosis (PLCA) is a skin condition characterized by amyloid deposition.
• Understanding the subtypes, epidemiological variations, and underlying composition of PLCA is crucial for diagnosis and management.

Purpose of the Study:

• To review and characterize cases of primary localized cutaneous amyloidosis (PLCA) in a Malaysian cohort.
• To compare the histological, clinical, and immunohistochemical features of papular amyloidosis (PA) and macular amyloidosis (MA).
• To investigate the ethnic distribution and potential associations of PLCA subtypes.

Main Methods:

• Retrospective review of 85 consecutive skin biopsies from Malaysian patients diagnosed with PLCA.
• Classification of cases into papular amyloidosis (PA) and macular amyloidosis (MA).
• Histological, tinctorial, and immunohistochemical analyses of amyloid deposits, including staining for AA protein, immunoglobulin light chains, keratin, cytokeratin, and AP protein.

Main Results:

• Out of 85 PLCA patients, 63 had PA and 22 had MA.
• PLCA was more frequent in Chinese patients; MA was more common in Indian patients.
• PA showed larger amyloid deposits in the papillary dermis compared to MA, but both subtypes were chemically similar, permanganate-resistant, negative for AA protein and immunoglobulin light chains, and showed strong AP protein immunoreactivity, suggesting an epidermal origin.

Conclusions:

• Papular amyloidosis and macular amyloidosis are histologically distinct but chemically similar subtypes of PLCA.
• Amyloid deposits in both PA and MA are likely of epidermal origin.
• PLCA exhibits varied ethnic predilection in Malaysia, with MA showing no association with other systemic diseases.