PracticalDermatology

A 53-year-old male presented with a 20-year history of rashing and severe pruritus on the left lower leg. He admitted to rubbing and scratching incessantly. Treatment with a variety of topical steroids and moisturizing lotions had proven ineffective. Physical examination revealed a 30cm x 10cm slightly scaled and hyperpigmented plaque studded with 1mm lichenified papules. (Figures 1 & 2)

Figure 1

Figure 2

Figure 3: Small, hyaline deposits of amyloid are situated in the papillary dermis. The overlying epidermis shows hyperkeratosis and acanthosis. (Hematoxylin & Eosin 40x)

A shave biopsy obtained from this lesion revealed moderate to marked acanthosis with elongation and broadening of the rete ridges, preservation of the granular layer, papillomatosis, and focal intercellular spongiosis. Hyperkeratosis and focal parakeratosis were seen. Dermal papillae were rounded and contained globular deposits of amyloid. A lymphohistiocytic perivascular infiltrate was present in the upper dermis, which was slightly fibrotic. (Figures 3, 4) Congo red stain with appropriate controls showed green birefringence. (Figure 5) Crystal violet stain with appropriate controls demonstrated positive staining with amyloid deposits in the papillary dermis. (Figure 6) These pathological findings in this clinical setting were consistent with lichen amyloidosis.

Figure 4: Highlighted pale-staining hyaline deposits of amyloid are noted in the papillary dermis in this higher power view. (Hematoxylin & Eosin 100x)

Figure 5: The amyloid deposits are highlighted in this crystal violet stain. (Crystal violet x 100)

Figure 6: The amyloid deposits can also be highlighted using Congo red staining, which exhibits apple-green birefringence when examined under polarized light. (Congo red x 100)

Discussion

Lichen amyloidosis is the most common variant of primary cutaneous amyloidosis (PCA) and is associated with the extracellular deposition of amyloid in the skin without associated internal organ involvement.¹ The amyloid deposits in PCA are keratinocyte-derived, primarily composed of keratinocyte 5. Most cases of PCA have been described in Southeast Asian, South American, and Chinese patients. The pathogenesis is not completely understood. Prolonged rubbing and friction are thought to be the primary etiologic factor, though Epstein-Barr virus has been demonstrated in a large number of cases of PCA. Rare familial cases have also been described.² Lichen amyloidosis may initially present as discrete hyperpigmented papules, while later clinical findings include persistent, pruritic, lichenified plaques. The most common location is the extensor surface of extremities, such as the shin or thigh.^2,3 Typical pathologic findings include pink amorphous deposits representing amyloid in the papillary dermis. The overlying epidermis is typically hyperkeratotic and acanthotic. Positive staining with congo red and crystal violet stains can assist with the diagnosis.^2,4

The authors have no relevant conflicts of interest.

Allison Cruse, MD is PGY3, Department of Dermatology, University of Mississippi Medical Center.

Joy King, MD, PhD is PGY3, Department of Pathology, University of Mississippi Medical Center

Leslie Partridge, NP is in the Department of Dermatology, University of Mississippi Medical Center

Robert T. Brodell, MD is Professor and Chair, Department of Dermatology, Professor and Interim Chair, Department of Pathology, University of Mississippi Medical Center

1. Wang WJ, Chang YT, et al. Clinical and histopathological characteristics of primary cutaneous amyloidosis in 794 Chinese patients. Zhonghua Yi Xue Za Zhi (Taipei). 2001; 64(2): 101-107.

2.Fernandez-Flores. Cutaneous amyloidosis: a concept review. Am J Dermatopathol. 2012; 34(1): 1-17.

3.Wang WJ. Clinical features of cutaneous amyloidosis. Clin Dermatol. 1990; 8(2): 13-19.

4.Elston DM, Ferringer T. (2014) Dermatopathology (Second edition). Philadelphia, Pennsylvania. Saunders.