JPC SYSTEMIC PATHOLOGY
Signalment (JPC #1454646): Dog
HISTOPATHOLOGIC DESCRIPTION: Testis and epididymis: Expanding the connective tissue of the epididymis are multiple granulomas, up to 3x6 mm, composed of a central area containing numerous degenerate spermatozoa and inflammatory cells, clear acicular clefts (cholesterol), and abundant eosinophilic cellular and karyorrhectic debris. This area is rimmed by a zone of lymphocytes, plasma cells, epithelioid macrophages, and rare multinucleated giant cells that is further surrounded by thin band of fibrous connective tissue. Multifocally within the surrounding connective tissue, there are few lymphocytes, plasma cells, and occasional macrophages, some of which contain granular, golden-brown pigment (hemosiderin). Within the epididymis there is diffuse aspermia. Within the testis, seminiferous tubules are degenerate with an undulant basement membrane, vacuolated Sertoli cells, and decreased amounts of mature sperm. Multifocally in the testis low numbers of similar inflammatory cells infiltrate and surround seminiferous tubules and there are rare multinucleated spermatids.
1. Epididymis: Sperm granuloma, multiple, breed not specified, canine.
2. Testis, seminiferous tubules: Degeneration, diffuse, moderate with hypospermatogenesis and lymphoplasmacytic orchitis, multifocal, mild.
- Reported in many domestic species and man
- May occur within the testes, efferent ductules, epididymis and vas deferens
- Predisposing factors include trauma, inflammation, congenital ductular abnormalities, adenomyosis of epididymal ducts, parasitic lesions, toxins and vasectomy
- Effects on fertility depend on the location and severity of the lesion
- Spermatozoa develop after immune system development
- Any defect, injury, infection, or degenerative change causing loss of epithelial and basement membrane integrity and exposes sperm antigens to the immune system can result in autoantibody formation with resultant sperm granulomas
- In Wistar rats, inhibition of phosphodiesterase-4 (PDE4) leads to sperm granuloma formation
- Ram studies found local immune response of IgG and IgM producing cells and T-helper cells early, followed by atypical foreign body reaction
- Congenitally blind efferent tubules can form pouches or cystic areas in which impaction and inspissation of sperm can occur, forming a spermatocele
- Sperm may become impacted in epithelial outpouchings of epididymal adenomyosis, causing similar lesions
TYPICAL CLINICAL FINDINGS:
- Chronic epididymitis: Fibrosis can cause hard nodules with testicular atrophy
- May have no effect on fertility when lesions are small and isolated to a single efferent ductule, or unilateral lesions that occlude sperm transport, if the contralateral testis is normal
TYPICAL GROSS FINDINGS:
- Irregularity of epididymal size and shape in comparison to contralateral sid
- Usually a single, hard epididymal nodule, although can be multiple
- Fibrinous or fibrous adhesions between epididymis and tunics
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Accumulations of spermatozoa and macrophages within tubules or the adjacent interstitium of efferent ductules or epididymis
- Ducts contain fibrin, neutrophils, disintegrating spermatozoa, damaged epithelium, macrophages, multinucleate giant cells with engulfed spermatozoa
- Macrophages form a distinct layer in the granuloma wall, external to the mass of extravasated spermatozoa
- Foreign body and Langhans type multinucleate giant cell macrophages
- Epididymitis due to Brucella ovis, Histophilus ovis or Actinobacillus seminis in rams
- Marked species variation in development of post-vasectomy sperm granulomas
- Rabbit, hamster, and monkey: Sperm granulomas usually do not appear for weeks to months after vasectomy; can occur anywhere along the epididymis and vas deferens
- Guinea pigs: Vasectomized animals develop autoimmune orchitis, rather than granulomas
- Spontaneous epididymal lesions in captive aged chimpanzees: lymphocytic infiltrates (3/14), hemosiderophages (2/14), and a sperm granuloma (1/14)
- Brinsko SP, Blanchard TL, Varner DD. Diseases of the reproductive system, male reproductive disorders. In: Smith BP, ed. Large animal internal medicine. 4th ed. St. Louis, MO: Mosby Elsevier; 2008: 1483.
- Chaffee BK, Beck AP, Owsteon MA, Kumar S, et al. Spontaneous reproductive tract lesions in aged captive chimpanzees. Vet Pathol. 2016;53(2):425-435.
- Foster RA. Male reproductive system. In: McGavin MD, Zachary JF, eds. Pathologic Basis of Veterinary Disease. 5th ed. St. Louis, MO: Mosby Elsevier; 2012: 1129, 1135, 1140-1141.
- Foster RA. Male genital system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 3. 6th ed. Philadelphia, PA: Saunders Elsevier; 2016: 480-481, 497.
- Heuser A, Mecklenburg L, Ockert D, Kohler M, Kemkowski J. Selective inhibition of PDE4 in Wistar rats can lead to dilatation in testis, efferent ducts, and epididymis and subsequent formation of sperm granulomas. Toxicol Pathol. 2013;41(4):615-627.