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DERM DX: What Is This Hyperpigmented Rash of the Posterior Neck, Back, and Legs?

DERM DX: What Is This Hyperpigmented Rash of the Posterior Neck, Back, and Legs?

A 50-year-old Indian male presented with a hyperpigmented, somewhat scaly rash on the posterior neck and back. A few similar appearing lesions were noted on the extremities (Figure 1). Before evolving to involve the posterior neck and back and to a lesser extent the forearm, the rash developed first 15 years ago on the lower legs as 2 round plaques (Figure 2). Prior to the development of this rash, the patient reported a chronic history of xerosis. The physical examination showed plaques of discrete and coalescing hyperkeratotic tan-brown papules suggestive of a resolving dermatitis with post-inflammatory hyperpigmentation on the lower extremities. The upper back and nuchal area showed similar changes at the periphery; however, exhibited areas of atrophic hypopigmentation with a subtle yellowish coloration at the center of the plaques.


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Diagnosis: Lichen Amyloidosis       

Lichen amyloidosis is a skin disorder that is relatively rare in the west, but presents more commonly in patients from Indonesia, Singapore, Taiwan, Thailand and some South American countries.1 It is the most common form of primary localized cutaneous amyloidosis, and due to its benign nature few studies have investigated the condition’s etiology, but it is believed to be induced by scratching in genetically susceptible individuals. Chronic scratching results in the characteristic deposition of amyloid in the papillary dermis. Unlike other systemic amyloidosis in which the amyloid is derived from immunoglobulins or serum proteins, the amyloid in lichen amyloidosis is derived from keratin peptides of necrotic keratinocytes.2 Lichen amyloidosis typically presents with multiple persistent, pruritic eruptions with firm, hyperpigmented and hyperkeratotic papules that can coalesce and produce a rippled appearance (Figures 1 and 2).3 


The key component of the histology is the deposition of pink amorphous material within the papillary dermis. Lichen amyloidosis is distinguished from macular amyloidosis by the presence of marked epidermal changes including hyperkeratosis and epidermal hyperplasia. 

Many stains can demonstrate the amyloid deposits in the skin, particularly the Congo red stain, which under polarizing light takes on a bright apple-green birefringence. Other less frequently used stains include periodic acid–Shiff, methyl violet, crystal violet, various cotton dyes (pagoda red, Sirius red) and fluorescent dyes (thioflavin-T and Phorwhite BBU).4 

Differential Diagnosis 

Erythema dyschromicum perstans, lichen planus actinicus, lichen simplex chronicus and other causes of lichenoid tissue reaction such as lichen amyloidosis all need to be considered in the differential diagnosis. The clinical diagnosis in this case was confirmed histologically.


Treatment of lichen amyloidosis is frequently exhaustive and usually ineffective. While it is unknown whether scratching develops first and leads to damage of keratinocytes and subsequent deposition of amyloid or if scratching is secondary to the deposits, most treatments are intended to alleviate the pruritus. Medical treatments primarily include local application of high-strength corticosteroids. Menthol in combination with antihistamine agents has also been used successfully to relieve itching. 

Less frequently used modalities include topical application of keratolytic ointments such as 10% dimethyl sulphoxide and oral administration of the aromatic retinoid etretinate (Tigason). Issues with some of these treatments include relapse after treatment is stopped (ie, etretinate) or a general lack of response at all for some patients.5

Surgical treatments such as dermabrasion and electrodesiccation have also been used in the management of lichen amyloidosis with varied success.6,7 In a study by Norisurgi et al,8 the authors describe a method that involves treatment of the affected area by superficial ablation using a CO2 surgical laser. The study found that the papules flattened and the patients observed significant improvement in pruritus. 

A second method proposed by Harahap et al1 describes a scraping technique that uses a scalpel to remove the deposits of amyloid in the dermis until the subpapillary dermal layer is reached. All 9 patients in the study healed with acceptable to good aesthetic results, with the only noted complication being mild hypopigmentation or hyperpigmentation, which became more inconspicuous with the passage of time.

Our Patient

Multiple biopsies were obtained from the posterior neck and left arm that revealed amorphous material in the papillary dermis with an associated lichenoid inflammatory infiltrate. (Figures 3-5). The left upper arm biopsy demonstrated findings consistent with post-inflammatory hyperpigmentation (Figure 3). The posterior neck biopsies revealed hyperkeratosis and dyskeratotic keratinocytes, as well as numerous melanophages and a patchy lymphohystiocytic inflammatory infiltrate. Congo red stain was performed which highlighted the amorphous material in the papillary dermis. The clinical and histologic findings support a diagnosis of lichen amyloidosis. The patient perceived slight improvement with the combination of topical clobetasol ointment and 12% ammonium lactate lotion.


Lichen amyloidosis is a form of primary localized cutaneous amyloidosis that presents with multiple pruritic eruptions with hyperpigmented and hyperkaratotic papules. The etiology is unknown but chronic scratching is thought to be the primary trigger for the deposition of amyloid in the papillary dermis. Treatment modalities, including topical steroids, are directed toward the alleviation of pruritus. 


Ms. Accetta is a student at Tulane University School of Medicine.

Dr. Helm is with State University of New York in Buffallo, NY, and clinical professor of dermatology and pathology at the University at Buffalo School of Medicine and Biomedical Sciences.

Figures 3-5. Multiple biopsies were obtained from the posterior neck and left arm that revealed amorphous material in the papilary dermis with an associated lichenoid inflammatory infiltrate. The left upper arm biopsy demonstrated findings consistent with post-inflammatory hyperpigmentation (Figure 3). Figure 4 shows a PAS stain and Figure 5 is a congo red stain.



Disclosure: The authors report no relevant financial relationships.


1. Harahap M, Marwali MR. The treatment of lichen amyloidosis. A review and a new technique. Dermatol Surg. 1998;24(2):251-254.

2. Weyers W, Weyers I, Bonczkowitz M, Diaz-Cascajo C, Schill WB. Lichen amyloidosis: a consequence of scratching. J Am Acad Dermatol. 1997;37(6):923-928.

3. Salim T, Shenoi SD, Balachandran C, Mehta VR. Lichen amyloidosus: a study of clinical, histopathologic and immunofluorescence findings in 30 cases. Indian J Dermatol Venereol Leprol. 2005;71(3):166-169.

4. Hashimoto K, Gross B, Lever W. Lichen amyloidosis: histochemical and electron microscopic studies. J Invest Dermatol. 1965;45(3):204-219.

5. Lim KB, Tan SH, Tan KT. Lack of effect of dimethyl sulphoxide (DMSO) on amyloid deposits in lichen amyloidosis. Br J Dermatol. 1988;119(3):409-410.

6. Aoki M, Kawana S. Lichen amyloidosis of the auricular concha: successful treatment with electrodesiccation. J Dermatol. 2009;36(2):116-117.

7. Wong CK, Li WM. Dermabrasion for lichen amyloidosus. Report of a long-term study. Arch Dermatol.1982;118(5):302-304.

8. Norisugi O, Yamakoshi T, Shimizu T. Successful treatment of lichen amyloidosis using a CO2 surgical laser. Dermatol Ther. 2014;27(3):71-73.

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