cow-2023-01

a) hemosiderophages (old hemorrhage)
b) Fungal infection
c) Malakoplakia
d) Blue nevus
e) Toxoplasma gondii latent infection

1. c

Toxoplasma gondii latent infection

Toxoplasma gondii is a protozoan parasite that infects most species of warm-blooded animals, including humans. Domestic cats and their relatives (family Felidae) are the definite hosts where sexual reproduction of T. gondii takes place. Humans (intermediate hosts) can become infected eating undercooked meat (of animals harboring tissue cysts), consuming food or water contaminated with cat feces or by contaminated environmental samples. Other infection routes are: transplacentally, blood transfusion or organ transplantation.

Immunocompetent persons exposed to Toxoplasma usually course with asymptomatic infection. About 10-20% develop a self-limited cervical lymphadenopathy and/or a flu-like illness. Immunodeficient patients may develop central nervous system disease or other conditions such as retinochoroiditis, pneumonitis, or other systemic disease. Toxoplasmic encephalitis is the most common cause of intracerebral mass lesions in patients with AIDS and is believed to be a reactivation of chronic infection. Acute primary Toxoplasma infections in pregnant women may result in congenital toxoplasmosis. Ocular toxoplasmosis is a common cause of retinochoroiditis and may be either congenital or acquired, and clinical manifestations may present decades after infection.
When a cat ingests meat containing tissue cysts, the cyst wall is dissolved by gastric and bowel enzymes releasing the bradyzoites. The bradyzoites (organisms in a slow multiplying stage) penetrate the epithelial cells of the small intestine and initiate the formation of numerous asexual generations before the sexual cycle. After the sexual cycle, a fertilized zygote originates the oocyst, which is excreted in the feces in an unsporulated stage. Sporulation occurs outside the body, and the oocysts are remarkably resistant and can survive in soil for months.
Some bradyzoites penetrate the intestinal lamina propria and begin to multiply as tachyzoites (fast multiplying stage). Tachyzoites may disseminate to extraintestinal tissues through the lymph and blood. They are responsible for acute illness and tissue damage. Tachyzoites can enter almost any type of host cell. This cycle may result in microfoci of tissue necrosis. The host usually overcomes this phase of infection, and the parasite then enters the “resting” stage in which bradyzoites are retained in tissue cysts. Tissue cysts are formed most in the brain, liver, and muscles. Tissue cysts usually cause no host reaction and may remain for the life of the host.
In a necropsy series of 80 patients with AIDS in Germany, necrotizing lesions of toxoplasmosis were seen in brain, heart, lungs, pancreas, adrenal glands and testis. Only intracellular cysts (bradyzoites) without tissue damage were documented in the gastrointestinal tract, liver, lymph nodes, spleen, prostate, kidney, and salivary glands (Jautzke et al. 1991). This was the unique report, to our knowledge, showing evidence of prostatic T. gondii infection in human necropsies. T. gondii has been documented in the prostate and male reproductive system of goats (Santana et al. 2010). The presence of oocysts with T. gondii bradyzoites has been diagnosed in prostate core biopsy in one previous report – in a patient with previous history of seizures and neurotoxoplasmosis and imunosupression due to HIV infection (Thoeni et al. 2020).

The histopathological diagnosis of T. gondii bradyzoites may include Histoplasma sp. (which stains by silver impregnation) and other protozoa such and Leishmania sp. and Trypanosoma sp. At Giemsa stain, the last two typically show a discrete kinetoplast.

The presence of only bradyzoites with no inflammation is indicative of latent infection. The medical history of the present of this case was unremarkable, he had negative HIV serology and thus those findings are favor the uncommon incidental finding of latent T. gondii infection.

Daher D, Shaghlil A, Sobh E, Hamie M, Hassan ME, Moumneh MB, Itani S, El Hajj R, Tawk L, El Sabban M, El Hajj H. Comprehensive Overview of Toxoplasma gondii-Induced and Associated Diseases. Pathogens. 2021 Oct 20;10(11):1351.

Jautzke G, Sell M, Thalmann U, Janitschke K, Iglesias J, Schürmann B, Ruf B. Immunhistologischer Nachweis der extrazerebralen Toxoplasmose bei AIDS [Immunohistochemical demonstration of extracerebral toxoplasmosis in AIDS]. Verh Dtsch Ges Pathol. 1991;75:185-8.

Santana LF, da Costa AJ, Pieroni J, Lopes WD, Santos RS, de Oliveira GP, de Mendonça RP, Sakamoto CA. Detection of Toxoplasma gondii in the reproductive system of male goats. Rev Bras Parasitol Vet. 2010 Jul-Sep;19(3):179-82.

Thoeni C, Margolis M, Toi A, van der Kwast T. Images in pathology: The *wild* prostate. Human Pathology: Case Reports Volume 21, September 2020, 200412

Daniel Athanazio
Professor of Medicine, Federal University of Bahia
Imagepat, Laboratory of Pathology
Salvador, Bahia, Brazil

Maiara Ferreira de Souza
Imagepat, Laboratory of Pathology
Salvador, Bahia, Brazil

Prostate

Prostate; Toxoplasma; Muscle, Smooth