Images of the month 4: Cutaneous amyloidosis: a clinical challenge

Discussion

Amyloidosis is defined by extra-cellular deposition of proteinaceous substance or various insoluble proteins that results in considerable tissue dysfunction. All types of amyloid consist of a major fibrillar protein that defines the type of amyloid plus various minor components. It may affect heart, kidney, gastrointestinal tract, nervous system and skin (dermal layer). It was first reported by Rudolph Virchow, German physician in 1854. Amyloidosis is usually classified as primary or secondary according to the underlying cause. Recent classification is based on biochemical findings (Table 1).

In this case clinical findings suggested primary localised cutaneous amyloidosis (PLCA). In this condition, there is deposition of amyloid in previously normal skin with no evidence of deposits in internal organs. Amyloids build up in the skin, specifically in the ‘dermal papillae’ between the epidermis and the dermis. It is associated with chronic friction or epidermal damage – friction amyloidosis. According to the clinicopathological observations, PLCA is classified as macular, papular or lichen amyloidosis, nodular or tumefactive and familial (dyschromic).

Macular form is presented with flat dusky-brown or grey macules that may coalesce with variable degree of itchiness. It is usually symmetrical and affects upper back, chest and occasionally arms. It presents in early adult life with female to male predominance. Pathological finding includes amyloid in papillary dermis with no involvement of blood vessels or adnexal structures. There are small amorphous globules. Epidermis has normal thickness.

Papular or lichen amyloidosis is the most common form. It presents with intense itchiness and multiple scaly red or brown papules that may coalesce into plaques. It is more common in males between 50–60 years old. Pathological finding includes focal deposits, large enough to expand dermal papillae displaced rete ridges.

The epidermis has irregular acanthosis and hyperkeratosis.

This case suggests macular form of PLCA although it differs from some usual clinical and pathological presentations.

Primary cutaneous amyloidosis has been reported in different body areas including eyelid¹ and the auricular concha.² Cutaneous amyloidosis may be associated with systemic amyloidosis. There are case reports of sarcoidosis and IgA nephropathy in association with extensive macular amyloidosis. At least a subset of PLCA patients, especially those with extensive involvement, may have associated autoimmune/immune disorders raising the possibility of a common underlying immune-mediated mechanism.³

Familial PLCA shows autosomal dominant inheritance, but there is clinical and genetic heterogeneity and variable clinical penetrance.⁴

Management of PLCA is challenging. In this case, patient was treated with potent topical steroid with no significant improvement. Other options include calcipotriol, phototherapy, dimethyl sulfoxide, etretinate, acitretin, cyclophosphamide, ciclosporin, cryotherapy, dermabrasion, CO₂ laser and surgical measures.