Case Study

Urethral obstruction, concurrent pleural effusion, and cranial mediastinal mass in a 10 year old MN DSH cat

A 10-year-old MN DSH with history of urinary blockage was presented for urethral obstruction. The cat had recently been unblocked and was currently on antibiotics. On physical examination the urinary bladder was distended, turgid, and non-expressible. The patient was treated with intravenous fluids and was unblocked. Five small stones were produced. Survey radiographs showed the presence of many small stones in the bladder and loss of the cranial cardiac detail. Subtle tachypnea was noted on clinical exam. Urinalysis showed normal pH and specific gravity, proteinuria, pyuria, hematuria, and calcium oxalate crystals. Abnormalities on CBC and serum biochemistry were leukocytosis and neutrophilia and hypercholesterolemia and hyperglycemia, respectively. Random blood glucose the following day was elevated (183 mg/dl).

DX

LN: hemorrhagic hypocellular aspirate and fat. Pleural effusion: hemorrhage and possible lymphocytic inflammation.

Sonographic Differential Diagnosis

Undefined pleural effusion with craniomediastinal lymphadenopathy non-cardiac related.

Image Interpretation

A mild to moderate amount of echogenic free thoracic fluid was noted in this patient with slight cranial mediastinal lymphadenopathy. Two lymph nodes that were enlarged together comprised 3.2 x 1.7cm. Fine needle aspirates of these lymph nodes were performed through the mediastinal fat. Thoracocentesis revealed hemothorax.

Outcome

The patient remained on fluids, antibiotics, and antispasmodics. Cytology from the aspirated thoracic lymph nodes revealed hemorrhagic hypo-cellular aspirate with fat. Analysis of the pleural effusion showed hemorrhage with a possible lymphocytic inflammation. The patient continued to do well and was discharged after several days of being hospitalized. Approximately one month later, patient presented to an emergency referral facility in critical condition. Physical examination found the patient dyspneic with labored breathing, decreased lung sounds, and hypothermic. Due to patient’s guarded condition and poor prognosis owners elected euthanasia.

Comments

When sampling these types of cases it is easy to get hemorrhage artifact in the sample. To avoid this issue, use a smaller needle on FNA, such as a 24-25 gauge needle. This will give a smaller sample, but a higher quality one. Also when a monopopulation of lymphocytes occur in a sample where lymphoma is suspected and the cytology interpretation is non definitive, consider the following: 1) Include the labeled ultrasound images with the cytology so the structural pathology is evident to the cytologist. 2) Get the sample reread and ensure a board certified cytologist is reading it. 3) Order PCR or PARR analysis for lymphoma on the slide, even if it is stained. (CSU or NC State labs perform this test and others may in the future) 4) Core biopsy the lymph node if a safe window is available. 5) Empirically treat for lymphoma. Prednisone and Leukeran work well with small cell lymphoma and with mature lymphocytic inflammation. Lymphoblastic or intermediate cells suggest a more aggressive form of lymphoma that will not respond readily to prednisone and Leukeran. In this case a definitive diagnosis was not achieved but the outcome was very consistent with thoracic lymphomatosis.

Clinical Differential Diagnosis

Urethral obstruction,
Respiratory signs: pleural effusion, cranial mediastinal mass, cardiac failure, pneumonitis.

Sampling

US-guided FNAs. Cytology from the aspirated thoracic lymph nodes revealed hemorrhagic hypo-cellular aspirate with fat. Analysis of the pleural effusion showed hemorrhagic transudate with lymphocytic inflammation.
Lymphoplasmacytic inflammation or lymphoma were the primary differentials.