**4.6 Other organs**

In the tongue, nodular deposition is seen, causing macroglossia. Gastrointestinal tract deposition of amyloid is common with polyps or ulcerative lesions. In the late stage, the cut surface shows yellow and waxy mural thickening. Clinically, it can cause motility disorders or stricture. Not uncommonly, vessels in the gastrointestinal tract can have amyloid deposition. In the respiratory tract, grossly nodular appearance is seen, and histologically, such depositions can be divided into four patterns including tracheobronchial, nodular parenchymal, diffuse alveolar septal, and lymphatic [11]. Skin depositions vary in size and shape, from papules to nodules and plaque. As an endocrine organ, the thyroid can present with goiter and is associated with medullary carcinoma. Localized nodular deposition in the bone causes amyloidoma. Inflammation including giant cell, lymphocyte, and spheroid structure has been reported [12]. Joint depositions are seen mimicking rheumatoid arthritis, but less synovial inflammation is seen. Bone marrow deposition is commonly seen in multiple myeloma patients. For patients on chronic dialysis, amyloid-related carpal tunnel has been seen.

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reactivity.

*Pathologic Findings of Amyloidosis: Recent Advances DOI: http://dx.doi.org/10.5772/intechopen.84268*

**4.7 Atypical amyloid findings**

**Figure 7.**

extracted into the surrounding tissue [18].

correlation cannot substitute for amyloid typing.

embedded (FFPE) section compatibility.

Cases of intracellular amyloid deposition have been reported in few organs including cardiomyocytes, plasma cells, as well as the histiocytes and β cells of the pancreas [12–14]. Spheroid type (corpora amylacea-like) amyloid deposition is reported in pituitary adenoma, squamous cell carcinoma of the uterine cervix, and amyloidoma of the bone, jejunum, and colon [15–18]. One case of spheroid type amyloid deposition from our group in association with colon adenocarcinoma is identified [2] (**Figures 6** and **7**). Current hypothesis regarding spheroid type amyloid deposition is that during the process of amyloid removal by macrophages, amyloid is packed inside the macrophage, making spheroid formations that are

*Spheroid type amyloid deposition in colonic submucosa, Congo red stain under polarizer filter.*

**5. Immunohistochemistry and immunoelectron microscopy**

While the Congo red stain positivity and birefringence are the gold standard of confirming amyloidosis, they do not tell what type of amyloid is deposited. Considering managements and clinical outcomes vary drastically according to the types, further studies to identify the causative protein are critical. Clinicopathologic

Immunohistochemistry (IHC) is the most commonly utilized method for subtyping amyloidosis. IHC takes advantage of relatively specific binding properties of antibodies against different types of amyloid fibrils to illuminate the amyloid protein in tissue. A panel of antibodies for more common types can subtype the majority of amyloidosis cases. Such antibodies include those against ALλ, ALκ, AHγ, ATTR, Aβ2M, and AFib (fibrinogen). The method has been widely used due to low cost, ease of use, rapid turnaround time, and formalin-fixed paraffin-

However, there is one important pitfall in IHC. Because of heterogeneity of amyloid fibrils, nonspecific staining is common, and this potentially complicates the interpretation. For instance, the antibody against Aλ is notorious for nonspecific staining of amyloid other than Aλ. This diagnostic pitfall mandates the use of multiple comparative IHC stains to separate the true diagnostic positivity from the nonspecific reaction. In comparative IHC, subtyping of amyloid is determined by the specific amyloid with the strongest immunohistochemical

**Figure 6.** *Spheroid type amyloid deposition in colonic submucosa, Congo red stain.*

*Pathologic Findings of Amyloidosis: Recent Advances DOI: http://dx.doi.org/10.5772/intechopen.84268*

*Amyloid Diseases*

**4.6 Other organs**

**Figure 5.**

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**Figure 6.**

*Spheroid type amyloid deposition in colonic submucosa, Congo red stain.*

can deposit within small-to-medium-sized arteries in the superficial cortex and leptomeningeal space and causes cerebral amyloid angiopathy. Cerebral amyloid angiopathy causes recurrent lobar hemorrhage. Furthermore, most Alzheimer's-

In the tongue, nodular deposition is seen, causing macroglossia. Gastrointestinal tract deposition of amyloid is common with polyps or ulcerative lesions. In the late stage, the cut surface shows yellow and waxy mural thickening. Clinically, it can cause motility disorders or stricture. Not uncommonly, vessels in the gastrointestinal tract can have amyloid deposition. In the respiratory tract, grossly nodular appearance is seen, and histologically, such depositions can be divided into four patterns including tracheobronchial, nodular parenchymal, diffuse alveolar septal, and lymphatic [11]. Skin depositions vary in size and shape, from papules to nodules and plaque. As an endocrine organ, the thyroid can present with goiter and is associated with medullary carcinoma. Localized nodular deposition in the bone causes amyloidoma. Inflammation including giant cell, lymphocyte, and spheroid structure has been reported [12]. Joint depositions are seen mimicking rheumatoid arthritis, but less synovial inflammation is seen. Bone marrow deposition is commonly seen in multiple myeloma patients. For patients on

affected brains show cerebral amyloid angiopathy as well.

*Amyloid plaque seen in Alzheimer disease, β amyloid antibody in IHC.*

chronic dialysis, amyloid-related carpal tunnel has been seen.

**Figure 7.** *Spheroid type amyloid deposition in colonic submucosa, Congo red stain under polarizer filter.*
