Cytologic, histologic, microbiologic, and electron microscopic characterization of a canine Prototheca wickerhamii infection

Abstract

A 7-year-old, neutered male, mixed breed (Poodle-type) dog was presented to the internal medicine service at Affiliated Veterinary Specialists in Gainesville, Florida, for evaluation of a several week history of intermittent, dry coughing that was unresponsive to doxycycline or trimeprazine/prednisolone. A recent onset of bilateral mucoid nasal discharge was noted, and at the time of presentation, both nares were ulcerated and swollen (Figure 1). The dog had no reported travel history. Physical examination revealed generalized lymphadenopathy-peripheral lymph nodes were approximately 2-3 cm and firm upon palpation. No cutaneous lesions were present, aside from the ulcerated nares. A biochemistry panel at that time revealed a decreased albumin concentration (1.8 g/dL, RI 2.3-4.0 g/dL) and increased alkaline phosphatase activity (441 U/L, RI 23-212 U/L). The hypoalbuminemia was attributed to a negative acute phase response, and the increased ALP was attributed to recent prednisolone administration. Prothrombin time and activated partial thromboplastin time were unremarkable. No overt abnormalities were noted on three-view thoracic radiography. Abdominal ultrasonography was within normal limits, with the exception of a moderately enlarged sublumbar lymph node. Fine-needle aspirates of both a submandibular and popliteal lymph node were submitted to the University of Florida for evaluation. On cytologic evaluation of both lymph nodes, numerous organisms were observed (Figure 2). These organisms were typically found within macrophages but also identified extracellularly. The pale to moderately basophilic structures had a very thin, clear halo and were generally round, sometimes oval, and rarely irregular in shape. Most organisms were between 5.5-7.5 µm in diameter.

Comparative study of immunohematological tests with canine blood samples submitted for a direct antiglobulin (Coombs’) test

“…In this study, both DAT+ and DAT- samples appeared hemolyzed, but the degree of hemolysis was higher in DAT+ samples, which may represent an artifact caused by in vitro lysis during shipment and storage (up to 5 days from collection). It is therefore not surprising to find discrepancies between Hb, PCV, and Hct values observed in the study reported here and in clinical practice [ 49 ]. When serum chemistry was available, we found hyperbilirubinemia more frequently in DAT+ dogs as expected in dogs with hemolytic anemia [ 46 ].…”

Protothecosis in the mucosa of the pharynx mimicking pharyngeal cancer in an immunocompetent individual: a case report

“…In the histopathological examination, characteristic morula forms are helpful for diagnosing protothecosis, but there can be a lack of such findings due to the period of their life cycle. The external capsule of Prototheca species and the wall of yeasts stain positive with Grocott’s methenamine silver and periodic acid-Schiff stains [ 15 ]. Thus, they may be mistaken for Candida or Cryptococcus species, as we experienced.…”