Clinical summary continued: In 1997, when the new lesion was first noted radiographically, serum protein electrophoresis showed no abnormalities. Further, in 1998, a urinary protein electrophoresis was normal. A fine needle aspiration biopsy of the new nodule was performed in 10/99. No further treatment is contemplated at this time.
Histologic Changes
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The biopsy tissue shown here was so firm that it had to be pushed out of the needle by a stylet. It is composed of a sparsely cellular, homogeneous, pink, extracellular material similar to that in the previous nodule. There was no evidence of malignancy.
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At higher magnification, homogeneous, pink material with cracks, which typically occur, replaces parenchyma. The tentative diagnosis is amyloidoma. What special stain is needed to confirm the diagnosis? Answer | ||||||
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What special stain is needed to confirm the diagnosis? Answer: A positive Congo red stain (shown here) viewed with polarized light (see below). A positive Congo red stain alone is not specific for amyloid. | ||||||
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When viewed with polarized light, two colors specific for amyloid are seen--light green and yellow. As one of the polarizing films is rotated, the green becomes yellow and the yellow, green. White birefringence (not shown here) is characteristic of collagen. | ||||||
Final diagnosis: This reaction confirms the diagnosis of nodular amyloidosis (amyloidoma), which is recurrent in this case.
Clinical summary
Image 3
