Diagnosis and classification of amyloidosis by an immuno-histological method

Histological characteristics of sternoclavicular beta 2-microglobulin amyloidosis and clues for its histogenesis

BACKGROUND

The pathogenesis of beta 2-microglobulin amyloidosis (A beta 2m) has yet to be fully elucidated.

METHODS

We describe the distribution and extent of A beta 2m deposition and macrophagic infiltration in cartilage, capsule, and synovium of sternoclavicular joints obtained postmortem from 54 patients after 3 to 244 (median 46) months of dialysis. Twenty-four nonuremic patients served as a control group. The diagnosis of amyloidosis (A) rested on a positive Congo Red staining (typical birefringence) and that of A beta 2m on positive immunostaining of the A deposits with a monoclonal anti-beta 2m antibody. The size of A deposits was measured.

RESULTS

A beta 2m was detected in 32 (59%), and non-beta 2m amyloid (Anon beta 2m) was detected in an additional 8 (15%) of the 54 dialyzed patients. A beta 2m deposits were present in the cartilage of all A beta 2m (+) patients (100%). They were localized solely in the cartilage in 27% of the cases, either as a thin patchy layer or as a continuous thicker layer (identified as stage I). A beta 2m was additionally present in the capsule and/or synovium without macrophages in 27% of the cases (identified as stage II). The correlation between the size of cartilaginous deposits and dialysis duration (P = 0.02) as well as with the prevalence (P = 0.03) and size of capsular deposits (P = 0.02) suggests that stage II is a later stage of A deposition. Clusters of macrophages were detected around capsular and synovial amyloid deposits in 46% of the cases (identified as stage III). The longer duration of dialysis in those with stage III as well as the relationship between the size of the A beta 2m deposits and the prevalence of macrophagic infiltration suggests that stage III is the last stage of A beta 2m deposition. Marginal bone erosions were observed in 9 out of 12 patients with stage III deposits. Their size was correlated with that of cartilaginous deposits (P = 0.01). Among the 24 control patients, Anon beta 2m was detected in 12 patients (cartilage 100%, capsule 8%, synovium 30%).

CONCLUSIONS

The earliest stage of A beta 2m deposition occurs in the cartilage. A beta 2m subsequently extends to capsule and synovium. These two first stages do not require macrophage infiltration. Macrophages are eventually recruited around larger synovial or capsular deposits in the final stage. Marginal bone erosions develop in this late stage.

Localized conjunctival amyloidosis associated with extranodal lymphoma

A 62-year-old man was found to have a large asymptomatic amyloid nodule of the conjunctiva. Within the next year, a diffuse mixed small and large cell lymphoma of his scapula developed with amyloid in its stroma. No abnormal serum or urine protein was found. Subsequently, rib and paraspinal masses appeared. After irradiation and chemotherapy, the patient died of bronchopneumonia, 3 years after onset. By immunostaining, the amyloid of both conjunctiva and scapular tumor was of polyclonal immunoglobulin (AL) type, most prominently IgG and lambda chains, with lesser staining for IgA and kappa chains. The tumor cells showed a similar pattern. To our knowledge, this is the first report of systemic lymphoma and localized conjunctival amyloidosis without a serum paraprotein, and the first such association with a lymphoma of this cell type. Immunotyping of conjunctival amyloidosis should be performed to guide the workup for possible systemic disease.

Chemical heterogeneity of amyloid in the carpal tunnel syndrome

140 biopsies from 108 patients afflicted with the carpal tunnel syndrome were studied, 27 of whom showed deposition of amyloid, in 6 of them to such an extent that the amyloid was considered significant in the pathogenesis of the carpal tunnel syndrome. Morphologically, vessels and ligaments were affected and especially the peritendinous structures. As it was always part of generalized amyloidosis, the amyloid in the carpal tunnel consisted immunohistologically of amyloid A in three cases (including one case with simultaneous amyloid deposition of the AA- and the AB-type), of amyloid A kappa in one case, of amyloid of prealbumin origin in seventeen cases and of AB-amyloid in eight cases. We also described for the first time the manifestation of generalized senile amyloidosis (ASs) in the carpal tunnel. Deposition of amyloid of beta-2-microglobulin type (AB) in the carpal tunnel was particularly frequent and massive.

Characterization of different amyloids with immunological techniques

We studied 71 cases of amyloidosis from the autopsy material of our institute. 17 cases were secondary amyloidosis of which 7 had initially been diagnosed as primary amyloidosis; all cases reacted positively with an anti-substance A antibody; 13 showed a suppression and 4 a strong reduction of the Congo red staining following tissue incubation in KMnO4. 25 cases were identified as primary amyloidosis of which 7 had initially not been recognized as such. In 16 cases amyloid deposits reacted positively with antibodies specific for the light chains of the immunoglobulins (3 X kappa, 13 X lambda). A monoclonal plasmacytic cell proliferation in the bone marrow was seen in 14 cases. In all cases deposits were KMnO4 resistant, but 1 case showed a slight reduction of staining intensity. 27 cases were cardio-vascular (senile) amyloidosis; in 20 cases at least 3 organs showed deposits; 12 cases had deposits in 5 and more organs. 2 cases were heredofamilial amyloidosis. In those 29 cases deposits reacted positively with an anti-prealbumin antibody, but were negative for AA and the light chains of the immunoglobulins; the Congo red staining remained strong in all cases when previously incubated in KMnO4. KMnO4-Congo red staining and antisera specific for AA, L-chains and prealbumin proved of value for classification of amyloidosis and for its organ distribution.

Isolation and characterization of a kappa amyloid fibril protein

The fibril in primary amyloidosis (AL) is composed of a monoclonal light chain or portions thereof. No unique primary structure has been identified that predisposes certain light chains to form amyloid fibrils. Currently, classification of amyloidosis is based on the biochemistry of the amyloid fibril. We determined the NH2-terminal sequence of an amyloid fibril and found it to be of the kappa I immunoglobulin subgroup. No structural alterations were detected to account for the conversion of the light-chain fragment to an amyloid fibril. Antiserum produced to the fibril protein did not react in immunodiffusion with purified LEP or MAG antigens, which are kappa I proteins. This antiserum may be directed to antigenic sites unique to the immunizing protein and is unable to recognize homologous proteins, rendering it unsuitable for immunochemical identification of amyloid deposits of light-chain origin. PAG represents the 10th reported variable kappa I amyloid fibril protein subjected to partial sequence analysis. Antisera that recognize antigenic determinants present in all members of an immunoglobulin subgroup need further development.

Amyloidosis of the tongue: a clinical and postmortem study

Based on the limited number of reports and our own experience, amyloid involvement of the oral tissues seems to be rather rare, the tongue apparently being the most favoured site. Three such patients have been described in the present treatise. All 3 patients proved to be suffering from multiple myeloma or its prestage. In a previous postmortem study, more than 35% overall incidence of amyloid involvement of the tongue has been reported. In our own postmortem study of 100 tongues not a single case of amyloidosis was encountered. This inconsistency can probably be explained by the different use of stains and their interpretation. Limited experience with immunohistochemical methods for subtyping amyloid has been presented.