Amyloid-Producing Odontogenic Tumors of the Facial Skin in Three Cats

Abstract

Amyloid-producing odontogenic tumors (APOTs) of the facial skin were diagnosed in 3 domestic cats. The neoplasms had the histopathological characteristics of the odontogenic tumor. The neoplastic cells were present in irregular islands, strands, and sheets. The peripheral neoplastic cells of the islands and strands were arranged in a palisading fashion, while the central cells were polyhedral to stellate and randomly arranged. Multiple spherules of homogeneous eosinophilic material were closely apposed to the neoplastic epithelial cells. The spherules stained with Congo red and produced an apple green birefringence under polarization microscopy, indicative of amyloid. Immunohistochemically, amyloid materials of the neoplasms reacted with polyclonal antibodies for ameloblastin, amelogenin, and sheathlin antibodies. Neoplastic epithelial cells also reacted with antiameloblastin, amelogenin, and sheathlin antibodies, with varied intensity. The histopathological and immunohistochemical characteristics of dermal neoplasms of the 3 cats were analogous to those of APOTs reported in the dog and the cat.

Identification of Ameloblastin as an Amyloid Precursor Protein of Amyloid-Producing Ameloblastoma in Dogs and Cats

“…Odontogenic ameloblast-associated protein, the amyloid precursor protein of human CEOT, was not detected. In addition, neither sheathlin nor amelogenin, which were immunohistochemically detected in animal APABs in previous studies [ 17 , 26 ], were detected in all cases in this study.…”

“…In this study, mass-spectrometry-based proteomic analysis extracted ameloblastin as a prime candidate for precursor protein of APAB, and immunohistochemistry showed evidence for the existence of ameloblastin in amyloid deposits of both cats and dogs. Several immunohistochemistry-based studies in canines and felines have shown that ameloblastin [ 17 , 26 , 28 ], sheathlin, and amelogenin [ 17 , 28 ] are present in amyloid deposits but are negative for antibodies to cytokeratins and vimentin [ 17 ]. The amyloid of APABs from a cat, dog, and Bengal tiger did not contain odontogenic ameloblast-associated protein-related peptides but rather an ameloblastin-like peptide; an N-terminal residue of ameloblastin was detected from collected amyloid deposits of these APAB cases [ 29 ].…”

“…In human CEOT, odontogenic ameloblast-associated protein has been identified as an amyloid precursor protein [ 2 ]. Although several immunohistochemistry-based studies have shown that ameloblastin [ 17 , 26 ], sheathlin, and amelogenin [ 17 ] are present in amyloid deposits, the amyloid precursor proteins of APAB have not yet been precisely identified. In the present study, we performed mass-spectrometry-based proteomic analysis of three dogs and two cats with APAB and identified ameloblastin as an amyloid precursor protein.…”

Accumulation of Innate Amyloid Beta Peptide in Glioblastoma Tumors

“…Previously, different amyloids were found in a variety of tumors. Different carcinomas have amyloid stroma [54,55], and odontogenic tumors are positive for thioflavin T and Congo Red staining and are also immunopositive for the enamel matrix protein ameloblastin [56,57,58]. Similarly, amyloid was reported in breast cancer tumors but was determined to be a localized amyloid light chain (AL) type (primary amyloidosis caused by ImG light-chain β-sheeting) [59,60].…”

Accumulation of amyloid beta in human glioblastomas

“…Conversely, some tissue-specific cancerous tumor types overproduce tissue-specific, aggregationprone proteins. For example, the amyloid in odontogenic tumors is immunopositive for the enamel matrix protein ameloblastin [15][16][17]. Unlike odontogenic tumors, the tumoral amyloidosis of bone is usually of β2M origin and almost always progresses to multiple myeloma [18].…”