A Case of Perifollicular Macular Amyloidosis

Macular amyloidosis is a common type of primary localized cutaneous amyloidosis. We present a case report of a 74-year-old patient with no significant past medical history who was evaluated for dark macules and pruritus for over a year. On exam, follicular-based brown macules on the upper and lower back, bilateral shoulders, and bilateral dorsal upper arms were noted. The morphology and distribution of follicular-based macules was unusual, so the differential included follicular lichen planus, follicular eczema, and macular amyloidosis. Punch biopsy showed deposits of eosinophilic fibrillary material along with pigmentary incontinence in the papillary dermis, consistent with macular amyloidosis. Additionally, there was some trapping of the adnexal structures with atrophy of the periadnexal fat in the reticular dermis. In macular amyloidosis keratin, intermediate filaments such as cytokeratin serve as the amyloid precursors which deposit in the superficial dermis. Characteristically, macular amyloidosis presents as hyperpigmented macules or patches, often in a "rippled" linear pattern. This case highlights a rare presentation of macular amyloidosis because of the atypical follicular involvement and emphasizes the variety of presentations for localized cutaneous amyloidosis. Additionally, new treatment options such as Janus Kinase inhibitors and their potential role in the pathological pathway are discussed.