Thanks to John Lewis, DVM, DAVDC, Past President of AVDS for submitting this weeks quiz of the month.
A 12-year-old neutered male French bulldog was presented for evaluation of a lingual mass on the left caudodorsal tongue. The mass was dark pink/red in color and measured 1.5 cm x 0.8 cm x 0.8 cm. The mass was found as an incidental finding by the pet’s primary care veterinarian. Mandibular lymph nodes were normal size and firmness bilaterally. On palpation, the mass was well circumscribed and its attachment to the tongue was as wide as the tumor. The adjacent tongue parenchyma felt normal on palpation.
What are some differential diagnoses for the mass on the tongue of this dog?
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Plasmacytoma, mast cell tumor, amelanotic melanoma, squamous cell carcinoma (unlikely due to lack of ulceration), rhabdomyosarcoma (unlikely due to non-invasive nature) and granular cell tumor, to name a few.
How would you approach this case?
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The characteristic appearance of the tumor made he author suspect a benign plasmacytoma as the etiology of the tumor.
The patient was placed under general anesthesia, and the tongue was palpated and the entire oral cavity, pharynx and were examined. A fine needle aspirate was performed and intraoperative cytology was done to assess for the possibility of plasmacytoma and to rule out mast cell tumor. Cytology was diagnostic for plasmacytoma, with round cells having eccentrically placed nuclei with coarsely stippled chromatin and moderate amounts of basophilic cytoplasm. The cells had mild to moderate amount of anisocytosis and anisokaryosis.
Based on this information, an excisional procedure was done with 0.5-1 cm margins. A CO2 surgical laser was used at 4 watts (continuous mode). The site was closed in two layers with 5-0 poliglecaprone on a tapered needle.
The excised piece was submitted for histopathology and the margins were determined to be clean.
What is the difference between plasmacytoma and multiple myeloma?
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In patients with multiple myeloma, clinicopathologic findings may include monoclonal gammopathy, nonregenerative anemia, Bence Jones proteinuria, and serum hyperviscosity. Radiographs may reveal bone lesions on the spine, ribs and other bones. Benign plasmacytomas are commonly seen as pink/red solitary masses of 1-2 cm in diameter on the dorsal tongue of dogs. Therefore the chance of this French bulldog’s tumor being a manifestation of multiple myeloma is low.