A Rare Case of Systemic AL Amyloidosis with Muscle Involvement: A Misleading Diagnosis

Figure 2

Presence of amyloid fibrils confirmed by electron microscopy. Muscle biopsy was routinely fixed in 2.5% glutaraldehyde in cacodylate buffer, postfixed in osmium tetroxide, and dehydrated and embedded in Araldite; thin sections were studied under Philips CM100 TEM fibrillary structures likely resembling amyloid fibrils in the perimysial pericapillary area (a) (bar = 0.1 µm); an endomysial capillary lumen with a lightly thicker wall without amyloid fibrils (b) (bar = 0.2 µm). Postembedding immunostaining with a polyclonal anti-kappa light chain antibody (Dako, 1 : 100) thin section was studied under a Jeol JEM-1400 Plus electron microscope (c).

(a)

(b)

(c)