Geriatric, Male, Canine, Pit Bull Terrier

This case was discussed in virtual Abdominal Rounds with Donald E. Thrall DVM, PhD, DACVR in, November 2020.

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History: There is a very large, firm, deeply fixed mass in the left inguinal region.  Cytology was inconclusive – suppurative inflammation.  The patient is cryptorchid.  There is hypoalbuminemia, hyperglobulinemia, and non-regenerative anemia.

Imaging: Right lateral and ventrodorsal views of the abdomen were acquired (Fig. 1).

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  • There are 2 ovoid soft tissue masses in the caudal ventral aspect of the abdomen.
  • A poorly defined soft tissue mass is present in the left inguinal region.
  • An amorphous opacity is noted to the left of midline at the level of L2 and L3, and of the right of midline at the level of T 13 and L1. These opacities correlate with what are thought to represent pedunculated cutaneous nodules at the ventral aspect of the abdomen.


  • Most likely the most caudal abdominal mass represents an enlarged prostate gland and the more cranial mass the displaced urinary bladder.
  • One possibility for the inguinal mass is an enlarged retained (cryptorchid) testicle; possibly neoplastic
  • The enlarged nipples are consistent with gynecomastia
  • Considering all of the clinical and imaging findings, the most likely diagnosis is development of a neoplasm, presumably Sertoli cell tumor, in an inguinal retained testicle with hyperestrogenism syndrome.


An excellent discussion of the association between retained testicle, Sertoli cell tumor and hyperestrogenism is available.1  In dogs, right-sided inguinal cryptorchidism is the most common form followed by right-sided abdominal cryptorchidism.2  Age and testicular ectopia are risk factors for the development of Sertoli cell tumor and seminoma.3  And, the incidence of Sertoli cell tumor and seminoma is approximately twice as high in dogs with unilaterally retained inguinal testicles as in abdominal cryptorchids.4  Approximately one-third of dogs with Sertoli cell tumor develop hyperestrogenism syndrome as a result of estrogen production by the tumor.5,6

Hyperestrogenism syndrome, irrespective of cause, is clinically characterized by a variety of genital and extragenital changes.  These include alopecia, bone marrow suppression (aplastic pancytopenia), feminization (gynecomastia, galactorrhea, redistribution of body fat, pendulous prepuce, linear preputial erythema, reduced libido, and attractiveness to other male dogs), atrophy of the contralateral testicle (in unilaterally affected dogs), epididymal adenomyosis, prostatomegaly, and squamous metaplasia of the prostatic epithelium.5-9.  It is the cystic hyperplasia of the prostate gland that results in the glandular enlargement that so commonly characterizes this syndrome.

Metastasis from Sertoli cell tumor occurs in <15% of dogs.10  Therefore, surgery can be curative in most patients and in metastasis-free dogs the signs of hyperestrogenism would resolve.


  1. Carreira VS, Langohr IM, Flavio Ferrari H and Luvizotto MCR.  Pathology in Practice.  J Am Vet Med Assoc 2012;241:55-57.
  2. Ciasca TC, Taylor AJ, Halfacree Z, Lamb CE.  What is your diagnosis.  J Am Vet Med Assoc 2015;246:1183-1185.
  3. Grieco V, Riccardi E, Greppiy GF, et al. Canine testicular tumours: a study on 232 dogs. J Comp Pathol 2008;138:86–89.
  4. Reif JS, Maguire TG, Kenney RM, Brodey RS.  A cohort study of canine testicular neoplasia.  J Am Vet Med Assoc 1979;175:719-723.
  5. Agnew DW, MacLachlan NJ.  Tumors of the genital system.  [In} Meuten D (ed) Tumors in domestic animals.  2017;5th ed, 707-708.  Ames IA:  John Wiley & Sons.
  6. Foster RA.  Male genital system.  [In] Maxie MG (ed) Jubb, Kennedy and Palmer’s pathology of domestic animals.  2016; 6th ed, 494-495.  St Louis MO: Elsevier.
  7. Kennedy PC, Cullen JM, Edwards JF, et al. Histological classifications of tumors of the genital system of domestic animals. In: World Health Organization international histological classification of tumors of domestic animals. Vol 4. Washington, DC: Armed Forces Institute of Pathology, 1998;17–18.
  8. Fan TM, Lourimier L. Tumors of the male reproductive system. In: Withrow SJ, Vail DM, eds. Withrow and MacEwen’s small animal clinical oncology. 4th ed. St Louis: Elsevier 2007;637–648
  9. Gross TL, Ihrke PJ, Walder EK, et al. Atrophic diseases of the adnexa. In: Skin diseases of the dog and cat: clinical and histopathologic diagnosis. 2nd ed. Ames, Iowa: Blackwell Science Ltd, 2005;480–517.
  10. Hayes HM Jr, Wilson GP, Pendergrass TW, et al. Canine cryptorchism and subsequent testicular neoplasia: case-control study with epidemiologic update. Teratology 1985;32:51–56

Photo by Jason Pofahl on Unsplash


  1. Three small sharply marginated ovoid nodular lesion with mild irregular margins are visible in the cranioventral aspect of the abdominal and in the region of the Xyphoid and in the region of the penis. The Os penis is not completely depicted in the lateral projection.
    In the left inguinal region there is a large ovoid ill defined homogeneous soft tissue opaque structure. The abdominal wall in this region is intact.
    The prostate is asymmetrically moderately to severely enlarged (left more than right) and displace a structure resembling the urinary bladder cranially, as well as the colon dorsally. The bowel convolut is displaced cranially and there is moderate crowding with mild focal peritoneal detail loss in the cranial abdomen. Both kidneys are not completly delineable.

    Large space occupying lesion in the region of the inguinal canal left – Most likely compatible with a severely enlarged kryptorchid, inguinal testicle. Other origin of the mass are much less likely. No signs of bowel loops herniation. Differentials for the testicle enlargement: neoplesia such as sertoli cell tumor (bone marrow suppression), seminoma or leydig cell tumor. Orchitis / Epididimitis (Brucellosis) or torsion less likely.
    Moderate to severe prostatomegaly – Differentials: prostatitis, prostatic or paraprostatic cyst, benign prostate hyperplasy, prostatic neoplesia.
    Multiple nodular cutaneous lesions.

    An abdominal ultrasound is advised.

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