Plasmocitoma extramedular intratraqueal em uma cadela
Ferronato, AmáliaCheng, Arthur ColombariSmaniotto, CrisanDahm, ViniciusDetoni, Pietra Malu FranzenerPinheiro, Lorena dos SantosPinheiro, Rafael RovarisViott, Aline de Marco
Background: Plasma cell tumors occur as a multiple myeloma or solitary plasmacytoma. This latter can present as bone and/or extramedullary. Solitary extramedullary plasmacytoma (SEP) is a type of plasma cells tumor and occurs outside the bone marrow, which is frequently diagnosed in canine skin tumors. In addition to the skin, organs of the respiratory, alimentary, and urinary tracts can be considered primary sites. When viewed macroscopically, extramedullary plasmacytomas are small single nodules, elevated and usually with a regular surface; and upon sectioning, well-delimited, non-encapsulated, white, and/or reddish. These tumors are also frequently associated with immunoglobulin overproduction and amyloid deposition. overproduction. Case: A mongrel bitch of unknown age that presented with respiratory symptoms was diagnosed through radiological examination as having a tracheal foreign body occluding 75% of the lumen. However, during the tracheotomy surgical procedure, a mass was found adhered to the tracheal mucosa. Surgical excision of the mass and adjacent tracheal rings was subsequently performed and the material was sent for histopathological examination. Macroscopic evaluation revealed the presence of a firm and whitish nodular structure measuring 1.0 × 1.2 × 1.5 cm. Histological evaluation of the tissue showed highly cellular, well-defined, and expansive neoplastic proliferation of round cells, which extended from the submucosal layer towards the lumen. The cells were organized in well-grouped bundles and trabeculae on scarce fibrovascular stroma, which were predominantly rounded and with borders sometimes distinct, sometimes indistinct. The cytoplasm ranged from scarce to moderate, eosinophilic, and homogeneous, with central to paracentral rounded nuclei with dense chromatin and sometimes evident nucleoli. Moderate anisokaryosis and anisocytosis, with rare presence of binucleated cells and mitotic figures. Based on the aforementioned findings, the presumptive diagnosis was an undifferentiated round cell neoplasm. After a subsequent immunohistochemical evaluation with positive staining for MUM1, CD45RA, and lambda immunoglobulin light chain, a final diagnosis of solitary extramedullary plasmacytoma of the trachea was suggested. Discussion: Although plasmacytoma is considered a common cutaneous neoplasm, reports of its occurrence in other tis-sues, especially the trachea as in the present case, are scarce. The anatomical location and expansive growth of this tumor, contributed to the patient's clinical symptoms, which were characterized by reduced air passage and difficulty breathing through the upper airway. Plasmacytoid tumors are typically easily recognizable due to the distinct morphological features of the plasma cells, which exhibit a whitish perinuclear halo, known as the Golgi complex. However, in cases where there is marked cellular pleomorphism, the cells may lose their typical features, leading to a more complex histological diagnosis. Complementary exams, such as immunohistochemistry, become essential in such situations. The use of specific antibodies such as MUM-1, CD20, CD18, CD45RA, CD79α, or IRF4 is invaluable in the diagnostic procedure, as they are sensitive and specific for plasma cell neoplasms. Combining histopathology with these specific markers ensures a more accurate diagnosis.
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