Bilateral Multifocal Soft Tissue Amyloidomas of the Lower Extremities

Sir,

Amyloidoma or tumoral amyloidosis fall within the category of localized amyloidosis, which may produce a nodular or tumoral pattern of extracellular deposition in a particular organ.[1] We herein report a new case of multifocal soft tissue amyloidoma (STA) occurring on the bilateral legs of an elderly female patient possibly due to accompanying primary biliary cirrhosis and Sjögren syndrome.

A 62-year-old Japanese female was referred to our department with multiple nodules on the bilateral lower extremities with an approximately 3-year duration. Her previous medical history included Sjögren syndrome and primary biliary cirrhosis for 10 and 7 years, respectively. The patient was not diabetic. There was no previous history of specific injuries or injections on the site of skin lesion.

On physical examination, multiple subcutaneous nodules were noted on the bilateral lower extremities (the inner aspect of the right lower leg measuring 6.0 × 4.5 cm, the inner aspect of the left lower leg measuring 6.0 × 5.0 cm, and the right pretibial area measuring 2.0 × 1.5 cm and 1.0 × 0.8 cm). Each mass was skin-colored, elastic, firm, and not tender [Figure 1a-c]. A surveillance computed tomography scan showed no other focus of disease. Sonography revealed a well-defined, multilobulated, and hypoechoic mass in the subcutaneous fat layer and hypovascularity in and around the mass, indicating a benign soft tissue tumor [Figure 1d and e]. Sonographic findings were consistent with those reported previously.[2] Incisional biopsy was performed, after which the nodule was located in the subcutis. Histopathology showed extracellular, eosinophilic proteinaceous deposits, which showed typical green birefringence under polarized light when stained with Congo red [Figure 1f-i]. These deposits contained small aggregates of lymphocytes and histiocytes, whereas plasma cells were scarce. The amyloid type was identified immunohistochemically as AL amyloid [Figure 1j-n]. These results were consistent with a diagnosis of STA. No surgical or medical intervention was planned at the time of this report. The nodules remained stable with no signs of systemic amyloidosis.

Figure 1.

Clinical appearances: (a) the right pretibial area; (b) the inner aspect of the right lower leg; (c) the inner aspect of the left lower leg. (d and e) Ultrasound images. (f-h) Histopathology stained with Congo red ((f), ×4, (g), ×400). (h) H and E at ×400. (i) Green birefringence under polarized light. (j and k) Immunohistochemistry showed positivity for AL (kappa)-type amyloid deposition using polyclonal (j) and monoclonal (k) antibodies. Immunohistochemistry showed negativity for AL (lambda)-type amyloid (l), transthyretin (m) and amyloid A (n)

STA in the lower extremities has rarely been reported. A case of multiple bilateral STA of the legs with a history of Raynaud phenomenon, autoimmune thyroiditis, and positive serum ANA and a case of solitary STA in the leg with primary biliary cirrhosis are similar to the present case.[2,3] STA in the lower extremities may be of AA-, AL-, or β-2 microglobulin-type amyloid. Our case is unique in that it was multifocal (four lesions in a bilateral distribution in the lower extremities, the most numerous to date) AL (kappa)-type amyloidoma with associated systemic autoimmune conditions. The present case may represent a reactive process as a consequence of autoimmune chronic inflammation in the setting of Sjögren syndrome and primary biliary cirrhosis. Although the clinical setting of chronic inflammation in the present case indicates AA amyloid deposition, immunohistochemical stains clearly indicated AL (kappa)-type amyloid deposition.

In conclusion, we herein report a rare case of multifocal soft tissue AL-type amyloidoma occurring on the bilateral legs of an elderly female patient possibly due to accompanying primary biliary cirrhosis and Sjögren syndrome.

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Conflicts of interest

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