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Systemic amyloidosis presenting as nail dystrophy (and inducing onychophagia in the reviewer)

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By Warren R. Heymann, MD
June 20, 2016

I admit it — I am plagued with onychophagia (nail biting). It is a life-long habit, and now that I’m 61, I presume that this foible will remain with me to the end. It is worse with anxiety — after reviewing the following articles, I’m down to the hyponychium!

Xu et al report the case of a 59 year-old man who presented with nails that displayed onychorrhexis, splitting and distal pterygium. There were no waxy papules, purpura, macroglossia, sclerodermoid changes, cutis laxa or bullae. The process started with the right third finger, but subsequently involved all fingernails and toenails over the next two years. He was treated for presumed lichen planus with topical steroids. When there was no response to treatment, a nail bed biopsy was performed which demonstrated amyloidosis. A subsequent work up for systemic amyloidosis ensued, with SPEP, UPEP revealing monoclonal free lambda light chain, and a bone marrow biopsy demonstrating 60-70% lambda restricted plasma cells, confirming the diagnosis of multiple myeloma (1).

Prat et al presented the case of a 70 year-old man with a history of anasarca, distal polyneuropathy and restrictive cardiomyopathy where the diagnosis of myeloma was suspected. Fat aspiration and a nerve biopsy was negative for amyloidosis Rather than perform a rectal biopsy, a decision was made to biopsy the nail beds because of the presence atrophic fingernails and toenails with longitudinal striations. The nail bed biopsies confirmed the presence of amyloidosis with Congo red stain and apple green birefringence. As in the first case, there were no other classical cutaneous features of amyloidosis. Inclusive of this case, the authors reviewed ten cases of amyloid-associated onychodystrophy. They state:

Five patients presented multiple myeloma; two patients presented monoclonal gammopathy; and three patients had no association with myeloma.

Eight patients had nail lesions associated with other skin or mucosal abnormalities typical of amyloidosis. In five of these cases, the nail lesion was the first manifestation. In one patient and in the present case, involvement of the nails for more than 3 years was the unique cutaneous sign of systemic amyloidosis (2).

The nail changes in both could have easily been misdiagnosed as lichen planus, trachyonychia, or twenty nail dystrophy. I am not advocating biopsying every patient with nail dystrophy to rule out myeloma. Indeed, having exclusive nail involvement is rare. However, when patients present with a dystrophy without other cutaneous features of either lichen planus or amyloidosis, and the changes are progressive or unresponsive to treatment, it would be prudent to have a nail bed biopsy performed.

I can only imagine how many patients I have examined over the years who have presented with a type of nail dystrophy. I know exactly how many times I have entertained the diagnosis of amyloidosis under these circumstances – zilch. My threshold for biopsying nail dystrophies has been officially lowered.

1. Xu J, et al. Nail dystrophy as the initial sign of multiple myeloma-associated systemic amyloidosis. J Cutan Pathol 2016; 43: 543-5.
2. Prat C. Nail dystrophy in primary systemic amyloidosis. J Eur Acad Dermatol Venereol 2008; 22: 107-9.

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