Lichen amyloidosis in an unusual location

Area of Science:

• Dermatology
• Pathology

Background:

• Primary localized cutaneous amyloidosis (PLCA) is a skin condition characterized by amyloid deposition in the dermis.
• While common forms of PLCA exist, presentation in unusual locations can pose diagnostic challenges.

Observation:

• A 61-year-old woman presented with skin-colored, firm papules on her upper lip and nasolabial folds.
• She had a history of systemic lupus erythematosus in remission, with no concurrent lupus lesions in the affected area.

Findings:

• Skin biopsy revealed amyloid deposits in the dermis, positive for Congo red stain and exhibiting apple-green birefringence.
• Immunohistochemistry showed positivity for cytokeratins (CK) 5 and 6, and negativity for CK 14. Kappa and lambda stains were equivocal.
• Systemic amyloidosis was excluded through further investigations, including a multiple myeloma screen and rectal biopsy.

Implications:

• This case highlights an unusual facial presentation of lichen amyloidosis, a common form of PLCA.
• The findings underscore the importance of considering PLCA in the differential diagnosis of facial papular lesions, even with a history of autoimmune disease.
• The specific immunohistochemical profile provides insights into the nature of amyloid deposition in this localized form.