Rather than being a systemic disease, AL amyloidosis may also present as a localised disease, where amyloid deposition is limited to a single organ. The specific area of the body affected depends upon the biochemical nature of the amyloid fibril protein and, as in systemic AL amyloidosis, light chain fragments may be involved. Localised AL amyloidosis may first be suspected on the basis of its location. Typical sites associated with localised AL amyloidosis include the brain, bladder, skin, urinary tract, conjunctiva, larynx and the tracheobronchial tree in the absence of systemic visceral dysfunction . For patients with localised AL amyloidosis, localised therapy and life-long monitoring are necessary, although these patients have been shown to have a normal life expectancy . The frequent association of multinuclear giant cells with localized amyloid deposits and the equal prevalence of κ and λ type deposits has led to the suggestion that the pathogenesis may differ from that of systemic amyloidosis .
Serum free light chains (sFLCs) have been evaluated in patients with localised amyloid disease attending the UK National Amyloidosis Centre, as presented in Table 28.1. An enlarged series of 235 cases, was reported by the same group in 2005 . Of the 162/235 patients with tissue biopsy data available, the fibril type was classified as AL in 100 cases (27% κ, 73% λ). The study concluded that localised AL amyloidosis is associated with a generally excellent prognosis.
Overall, elevated levels of sFLCs are less commonly observed in localised amyloidosis than in systemic AL amyloidosis and, even when present, the concentrations are lower. sFLC concentrations may therefore assist in distinguishing the different types of amyloid disease and also systemic from localised light chain amyloid disease.
|Site of amyloid deposits||Number of patients||Monoclonal proteins*||Abnormal κ/λ sFLC ratios|
|Bone||7||3 (43%)||6 (88%)|
|Bladder||25||1 (4%)||3 (12%)|
|Bowel||10||4 (40%)||3 (30%)|
|Bronchial||13||2 (15%)||1 (8%)|
|Nodular pulmonary||13||3 (23%)||3 (23%)|
|Nasopharynx||16||1 (6%)||2 (13%)|
|Skin||18||2 (11%)||2 (11%)|
|Ocular||10||2 (20%)||2 (20%)|
|Lymph node||16||3 (19%)||5 (31%)|
Table 28.1. Frequency of monoclonal proteins in patients with localised amyloid disease. *Serum monoclonal proteins or light chain proteinuria identified by electrophoretic tests . (Courtesy of P. Hawkins)