Amyloidosis; five cases of primary generalized amyloidosis and some other unusual cases

Germ line origin and somatic mutations determine the target tissues in systemic AL-amyloidosis

BACKGROUND

Amyloid is insoluble aggregated proteins deposited in the extra cellular space. About 25 different proteins are known to form amyloid in vivo and are associated with severe diseases such as Alzheimer's disease, prion diseases and type-2 diabetes. Light chain (AL) -amyloidosis is unique among amyloid diseases in that the fibril protein, a monoclonal immunoglobulin light chain, varies between individuals and that no two AL-proteins with identical primary structures have been described to date. The variability in tissue distribution of amyloid deposits is considerably larger in systemic AL-amyloidosis than in any other form of amyloidosis. The reason for this variation is believed to be based on the differences in properties of the amyloidogenic immunoglobulin light chain. However, there is presently no known relationship between the structure of an AL-protein and tissue distribution.

METHODOLOGY/PRINCIPAL FINDINGS

We compared the pattern of amyloid deposition in four individuals with amyloid protein derived from variable light chain gene O18-O8, the source of a high proportion of amyloidogenic light chains, and in whom all or most of the fibril protein had been determined by amino acid sequencing. In spite of great similarities between the structures of the proteins, there was a pronounced variability in deposition pattern. We also compared the tissue distribution in these four individuals with that of four other patients with AL-amyloid derived from the L2-L16 gene. Although the interindividual variations were pronounced, liver and kidney involvement was much more evident in the latter four.

CONCLUSIONS/SIGNIFICANCE

We conclude that although the use of a specific gene influences the tissue distribution of amyloid, each light chain exhibits one or more determinants of organ-specificity, which originate from somatic mutations and post-translational modifications. Eventual identification of such determinants could lead to improved treatment of patients with AL amyloidosis.

Bilateral amyloid tumours of the breast

An 82 year old woman with bilateral amyloid tumours of the breast is described. Clinically, the breast masses were hard and were suspicious of carcinoma. Investigation revealed no evidence of systemic amyloidosis or amyloid related illness. Microscopically there was no neoplasia. Instead there was extensive fibrosis with amyloid deposition in perivascular periductal areas and also in the intervening stroma. The presence of amyloid was confirmed by special stains and by electron microscopy.

Primary (AL) amyloidosis as a cause of breast masses

Amyloidosis is rarely considered in the differential diagnosis of breast masses. During the past six years, 27 women with primary (24) and multiple myeloma-associated (three) amyloidosis (AL amyloid) were evaluated at our center. In five of these patients, amyloid was demonstrated on microscopic examination of breast tissue. The clinical presentations were similar to fibrocystic breast disease in two cases and malignancy in two others. Amyloidosis of the breast may be more common than previously recognized, especially considering the predilection of amyloid for depositing around fat cells. Therefore, pathologic examination of nonmalignant breast tissue should include Congo red staining and viewing under polarized light.

Tamm-Horsfall protein in lymph nodes

We found masses of amorphous waxy pale staining material in the peripheral sinuses of lymph nodes removed with renal tumors. The material was histochemically and immunohistochemically identical to Tamm-Horsfall protein. It was found also in tubular casts, renal tubules, and intrarenal lymphatics in the resected kidneys. Tamm-Horsfall protein was restricted to the compressed residual kidney and was not seen in the tumors. Under certain circumstances Tamm-Horsfall protein escapes from the tubules into the renal interstitium and may produce a local inflammatory reaction. It also gains access to intrarenal lymphatics and thence to regional lymph nodes. This may be relevant to the evolution of an antibody response.

Microscopic amyloid deposits in the heart valves: a common local complication of chronic damage and scarring

The presence of amyloidosis was detected in 33 out of 213 (15.5%) mitral and aortic valves that had been surgically removed for chronic valvular disease. No correlation could be found with age or type of valvular disease, neither was there any clinical evidence of an associated generalised amyloidosis. Histologically, the amyloid deposits were microscopic and restricted to areas of dense scar tissue. No comparable alterations were found in 147 unaltered valves which served as controls. The term 'dystrophic' is proposed to describe this particular form of valvular amyloidosis.

An amyloid lung

A 55-year-old housewife died from an illness characterized by progressive respiratory incapacity. Changes were confined to the lungs and consisted of a diffuse infiltration by amyloid. No adequate cause was found for this amyloid, and we suggest that this is a case of primary alveolar septal amyloidosis.

SYSTEMIC EFFECTS OF NON-ENDOCRINE TUMOURS

Tumours of non-endocrine origin may exert deleterious effects by elaborating active principles which disturb body regulation. Systemic manifestations are fairly common with neoplasms of the lung, kidney, gastro-intestinal tract and thymus. The secretion of these tumours may have a known chemical structure (serotonin), may present hormone-like action (parathormone, antidiuretic hormone, insulinoid), or have well-defined biological properties (erythropoietin, gastrin-like principle). Tumours may stimulate endocrine glands by an unknown mechanism, producing disorders such as Cushing's syndrome, hypercalcemia, gynecomastia and hypoglycemia. Thymomas may be associated with autoimmune diseases. Tumours may extensively utilize or excrete some metabolite (glucose) or electrolyte (Na or K). Awareness of the systemic effects of various neoplasms may lead to an early diagnosis and proper treatment of these manifestations.

Primary amyloidosis: a review

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