Urinary bladder wall mass with neoplastic lymphoid cells in the urine: Diagnosis of an IgG secretory B-cell lymphoma with Bence-Jones proteinuria in a dog.

In this study, we describe a multimodal approach to diagnose a unique case of myeloma-related disease, extranodal secretory B-cell lymphoma with urinary bladder involvement, an IgG4 monoclonal gammopathy, and Bence-Jones proteinuria in a dog with a 6-year history of hyperglobulinemia that had not been further evaluated. A 12-year-old dog was presented for evaluation of a 1-week history of tenesmus. Urine sediment cytologic evaluation revealed low to moderate numbers of intermediate to large-sized lymphocytes. We describe a technique that yielded adequate numbers of viable neoplastic cells in shipped urine sediment for PARR and flow cytometry. Those studies demonstrated a clonal immunoglobulin gene rearrangement and an expansion of CD21-positive and MHC Class II-negative B cells, respectively. Protein electrophoresis with immunofixation and proteomic evaluation revealed a serum and urine IgG4 monoclonal gammopathy with Bence-Jones proteinuria. MUM1 immunocytochemistry performed on the urine sediment slides failed to label the neoplastic cells; thus, a plasma cell tumor was considered unlikely. Lack of response to a cyclophosphamide, vincristine, and prednisone chemotherapy regimen led to euthanasia without necropsy 21 days after diagnosis. Lymphoma is the most common hematopoietic malignancy and accounts for up to a quarter of all neoplasms in dogs, but lymphoid neoplasms arising primarily from extranodal sites are infrequently reported. Urinary tract neoplasia can be diagnosed by urine evaluation in about one-third of canine cases, but the diagnosis of lymphoid neoplasia via urine evaluation is rarely reported. This case highlights the utility of ancillary diagnostics on urine for detection of lymphoid malignancies.

Retroperitoneal abscess and splenitis with Clostridium spp. in a dog.

An 11-year-old spayed female Basset Hound was presented to the Colorado State University Veterinary Teaching Hospital for evaluation of a 7-week history of intermittent collapse, waxing and waning lethargy, and hyporexia. Abdominal ultrasound revealed a 6-mm hypoechoic splenic nodule that, on cytologic evaluation, revealed marked neutrophilic inflammation with intracellular and extracellular bacterial rods frequently producing oval subterminal to terminal endospores, suggestive of Clostridium. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) performed on bacteria isolated from this nodule initially identified a Clostridium species, which was eventually confirmed with 16 s rDNA sequencing. Computed tomography (CT) and exploratory laparotomy subsequently identified a 2.5-cm diameter tubular structure beginning at the caudal aspect of the right kidney and coursing caudally containing gas and fluid, consistent with a retroperitoneal abscess, which was resected and also cultured Clostridium spp. The dog was discharged 3 days postoperatively and was alive at the time of writing, 7 months after discharge. This case highlights a previously unrecognized bacterial agent in a retroperitoneal abscess. The use of cytologic evaluation yielded a diagnosis of endospore-forming bacteria suggestive of Clostridium sooner than culture and histopathology, which allowed for adjustment in the antibiotic protocol.

Histoplasmosis and multicentric lymphoma in a Nubian goat.

Following treatment for pneumonia, a 1-y-old female Nubian goat was presented because of a persistent fever for 3 mo and peripheral lymphadenopathy for 1 mo. Cytology and histology of the superficial cervical and prefemoral lymph nodes demonstrated a moderate-to-marked "left-shifted" lymphoid population, suggestive of lymphoma, and extremely rare extracellular, 2-4 µm, oval, basophilic yeast, consistent with Histoplasma capsulatum. On immunohistochemistry, >95% of the lymphocytes demonstrated positive cytoplasmic and membranous immunoreactivity for CD3. Histoplasma spp. urine antigen and serum antibody testing were positive and negative, respectively. Panfungal PCR and sequencing of DNA extracted from scrolls of formalin-fixed, paraffin-embedded tissue yielded matches to H. capsulatum with 99-100% identity. Given the poor prognosis and persistent pyrexia, the animal was euthanized. Postmortem examination confirmed concurrent multicentric, intermediate-size, T-cell, lymphoblastic lymphoma and histoplasmosis; lesions consistent with intestinal coccidiosis and suspected pulmonary Rhodococcus equi were also noted. Although dimorphic fungi have been described previously in goats, lesions of Histoplasma spp. had not been documented in this species, to our knowledge. Given the low disease burden, it is suspected that the lymphoma was primary, leading to an immunocompromised state and development of secondary, opportunistic infections.