Primary lymphoma of the uterine horn in a Lhasa Apso dog

Abstract

Primary lymphomas of the canine female genital tract are uncommon tumours. A 9-year-old intact female Lhasa Apso dog presenting with a closed pyometra underwent an ovariohysterectomy (OHE), and the hyperplastic uterine horn along with multiple follicular cysts on the right ovary was examined by histological analysis. Severe infiltration of medium-sized lymphocytes with strong positive immunoreactivity for CD79a and numerous anaplastic features was detected in the unilateral uterine horn, and the dog was diagnosed as having extranodal marginal zone B-cell lymphoma (MZBCL). The present case reports an extremely rare occurrence of primary lymphoma involving the uterine horn in a dog and describes histological characteristics of the tumour for definite diagnosis.

Figure 1

Massive infiltration of lymphocytes in the endometrial lesion accompanying muscular infiltration (haematoxylin and eosin, bar = 100 μm).

Figure 2

Morphologic characteristics of tumour cells. The cells had relatively abundant cytoplasm and pleomorphic central to eccentric nuclei. The chromatin is coarse in general, and multiple prominent nucleoli were observed (haematoxylin and eosin, bar = 10 μm).

Figure 3

Positive immunoreactivity for CD79a in the cytoplasm of lymphocytes. Mayer’s haematoxylin counterstaining (bar = 50 μm).