Congenital interstitial cell tumor in an Angus/Holstein calf
Emily Brouwer, Steve Crawford
Animal Health Laboratory, University of Guelph, Guelph, ON (Brouwer), Crawford Veterinary Services, Atwood, ON (Crawford).
AHL Newsletter 2026;30(3):8.
An Angus/Holstein cross calf was presented for examination at approximately three weeks of age due to an enlarged testis (Fig. 1 & 2). The producer reported that the testis had been enlarged since birth, and apart from this abnormality, the calf showed no other significant clinical signs. There was no appreciable change in size since birth, nor did the animal show any significant discomfort. On clinical examination, the calf was diagnosed with unilateral cryptorchidism, with marked enlargement of the descended testis. Due to the absence of external signs of trauma, and the palpable firmness of the testis, possible differential diagnoses of scrotal hematoma and scrotal hernia were ruled out. The animal was routinely castrated, and the testis was incised for examination by the submitting veterinarian prior to subsampling for histology.
Figures 1 and 2. Affected calf with markedly enlarged testis
On gross examination, the testicular architecture was replaced by a multinodular, tan-red mass supported by bands of fibrous connective tissue and separated by cystic spaces containing serosanguinous fluid (Fig. 3 & 4).
Figures 3 and 4. Bisected testis. On cut section, the mass is both multinodular and cystic, with thick bands of fibrous connective tissue. There is no recognizable testicular tissue present.
Histologically, the tissue examined was comprised almost entirely of a multinodular, partially encapsulated, expansile mass formed of neoplastic polygonal cells arranged in sheets and cords supported by a fine fibrovascular stroma. Nodules of neoplastic cells were separated by bands of fibrous connective tissue that contained dilated vascular spaces. Neoplastic cells had distinct cell margins, abundant finely granular eosinophilic cytoplasm, and a single round central nucleus with finely stippled to vesicular chromatin and a single prominent nucleolus. There was up to two-fold anisocytosis and anisokaryosis, and there were zero mitotic figures in ten consecutive 400X power fields/2.37 mm2 (Fig. 5). Throughout the sections were patches of hemorrhage, or loose aggregates of fibrin and proteinaceous fluid containing mineralized cellular debris and neutrophils. The combined gross and histologic features were diagnostic for an interstitial cell tumor.
Figure 5. Testicular mass, 10X Hematoxylin & Eosin.
Congenital neoplasms are sporadically reported in cattle, and are typically associated with abortions, or perinatal/neonatal mortality. Most congenital tumors in cattle are malignant lymphomas, mesotheliomas, and embryonal tumors. Overall, tumors of mesenchymal origin predominate. Of congenital tumors reported to arise in the testis in bovines, sertoli cell tumors and yolk sac tumors predominate in this species. The cause of congenital tumors is not well understood, and potential causes include genetic abnormalities, infectious diseases, or toxin exposure.
Interstitial cell tumors are occasionally reported in bovines, particularly Guernseys, and tend to occur in older bulls. These tumors are almost invariably benign, with a slow and expansile growth habit. In Guernsey cattle, there is an association with interstitial cell tumors, thyroid C cell tumors, infertility and hepatic telangiectasis, but a causative relationship has not been established.
This particular tumor is exceptionally rare as a congenital lesion in cattle, with only one single animal case report identified in the literature. This case of congenital interstitial cell tumor was reported as an incidental finding in a 1-month-old, bilaterally cryptorchid shorthorn bull calf who presented to a veterinary teaching hospital for diarrhea and inappetence. There are no reports in the literature of a calf presenting with this tumor in a descended testis. Following castration, this calf is reported to be healthy and thriving.
References
1. Foster, RA and Premanandan, C. Chapter 5: Male Genital System. In: Jubb, Kennedy and Palmer’s Pathology of Domestic Animal 7ed, Volume 3. Maxie, MG ed. Elsevier, 2026: 467-508.
2. López A, Ikede B, Ogilvie T. Unilateral interstitial (Leydig) cell tumor in a neonatal cryptorchid calf. J Vet Diagn Invest. 1994 Jan;6(1):133-5
3. Sosa E, Giannitti F, Macías-Rioseco M, et al. Congenital neoplasms in cattle: a literature review and multi-institutional case series. Journal of Veterinary Diagnostic Investigation. 2025;37(4):559-573