Anorchia, also known as embryonic testicular regression is characterized by the unilateral or bilateral absence of functioning testicular tissue in an individual who has 46, XY karyotype and is phenotypically male [1] [2] [3]. The congenital form has an incidence of one in twenty thousand [4] while an acquired form has been identified based on the presence of testicular tissue in the postnatal period but which disappears later [5]. Anorchia has also been reported in one out of 175 cases with cryptorchidism [6]. It is known to have a familial tendency [1] [4] [7] [8]. The etiology of the condition is still being debated with several proposed theories ranging from genetic to 46, XY abnormal gonads [9] to vascular occlusion during embryonic testicular descent [10].

Most patients with anorchia present with normal male external sexual characteristics but may also present with microphallus [11], ambiguous external genitals [7], and feminine appearance of external genitalia [12]. Cases of neonatal testicular torsion as a presenting symptom has been reported by various authors [11] [12]. Individuals with bilateral anorchia typically develop normally but the onset of puberty is either delayed or absent depending on the extent of functioning testicular tissue in the body. Therefore secondary sexual characteristics may develop partially or not at all. Other organ anomalies like renal ectopia can also be present in these individuals [12] [13] along with low bone density.

A clinician should suspect anorchia if a patient presents with complaints of delayed puberty and has masculine external genitals but no palpable testes. A thorough family history must be elicited as other family members are also likely to have complete or partial gonadal abnormalities with 46, XY karyotype [12]. Physical examination may reveal microphallus [14] or normal external male genitalia with bilateral or unilateral palpable intrascrotal [11] [12] or inguinal masses [11] or no palpable masses [12].

Confirmation of the diagnosis requires hormonal evaluation such as gonadotrophin-releasing hormone (GnRH), follicle stimulating hormone (FSH), luteinizing hormone (LH), testosterone, inhibin B levels and provocation test with human chorionic gonadotrophin (hCG). In bilateral anorchia, low levels of testosterone along with elevated FSH levels and an absence of a rise in levels of testosterone after hCG [14] [15] [16] [17] is noticed. hCG provocation test is not required in 46, XY patients with elevated FSH and undetectable levels of anti-müllerian (AMH) and inhibin B as this scenario is diagnostic for anorchia [12].

Although ultrasonography can be performed as part of the workup, it cannot distinguish between testis and inguinal lymphadenopathy. Magnetic resonance imaging (MRI) is more useful for detecting testicular tissue especially if cryptorchidism is suspected. But imaging studies may not be required if hCG provocation fails to cause a rise in plasma testosterone levels [18].

Some authors have suggested surgical exploration for the testicular tissue as the most definitive method of diagnosis [19] especially in unilateral anorchia [17]. However, others [5] suggest that surgery is unnecessary in the workup of bilateral anorchia if endocrine tests confirm the absence of functioning testicular tissue.

Treatment for anorchia focuses on hormone replacement therapy (HRT) to ensure normal development and maintain health. Testosterone replacement can help develop secondary sexual characteristics and support bone and muscle health. Psychological support and counseling may also be beneficial, especially during adolescence, to address any emotional or social challenges.

With appropriate treatment, individuals with anorchia can lead healthy lives. Hormone replacement therapy can effectively manage symptoms and support normal development. However, fertility may be affected, particularly if both testes are absent. In such cases, assisted reproductive technologies may be explored if the individual wishes to have children.

The exact cause of anorchia is not well understood. It is believed to occur due to a disruption in the development of the testes during fetal growth. This disruption can happen due to genetic factors, environmental influences, or vascular accidents that affect blood supply to the developing testes.

Anorchia is a rare condition, with an estimated occurrence of 1 in 20,000 male births. It can affect individuals of any ethnic background. Due to its rarity, comprehensive epidemiological data is limited, and much of the understanding comes from case studies and small cohort studies.

The pathophysiology of anorchia involves the failure of testicular development during the critical period of fetal growth. Normally, the testes develop from the genital ridge in the embryo. In anorchia, this process is interrupted, leading to the absence of one or both testes. This absence results in a lack of testosterone production, affecting male sexual development and fertility.

Currently, there are no known preventive measures for anorchia, as the condition is believed to arise from complex genetic and developmental factors. Early diagnosis and intervention are crucial to managing the condition effectively and minimizing its impact on development and quality of life.

Anorchia is a rare condition characterized by the absence of one or both testes at birth. It can lead to hormonal imbalances and affect sexual development and fertility. Diagnosis involves physical exams, imaging, and hormonal tests. Treatment primarily includes hormone replacement therapy to support normal development. While the exact cause is unclear, early intervention can help manage symptoms and improve quality of life.

If you or someone you know is affected by anorchia, it's important to understand that with proper medical care, individuals can lead fulfilling lives. Hormone replacement therapy can help manage symptoms and support normal development. It's also beneficial to seek support from healthcare professionals and counseling services to address any emotional or social challenges. Remember, you're not alone, and there are resources available to help you navigate this condition.

1. Abeyaratne MR, Aherne WA, Scott JES. The vanishing testis. Lancet. 1969;2: 822–824.
2. Sarto GE, Opitz JM. The XY gonadal agenesis syndrome. J Med Genet. 1973; 10:288–293.
3. Edman CD, Winters AJ, Porter JC, et al. Embryonic testicular regression. A clinical spectrum of XY agonadal individuals. Obstet Gynecol. 1977;49:208–217.
4. Bobrow M, Gough MH. Bilateral absence of testes. Lancet. 1970;1: 366.
5. Teo AQA, Khan AR, Williams MPL, et al. Is surgical exploration necessary in bilateral anorchia? Journal of Pediatric Urology. 2013; 9: e78-e81
6. Aynsley-Green A, Zachmann M, Illig R, et al. Congenital bilateral anorchia in childhood: a clinical, endocrine and therapeutic evaluation of twenty-one cases. Clin Endocrinol. (Oxf).1976;5:381–391.
7. Josso N, Briard ML. Embryonic testicular regression syndrome: variable phenotypic expression in siblings. J Pediatr.1980; 97: 200–204.
8. Naffah J. Familial testicular regression syndrome. Bull Acad Natl Med. 1989;173:709–714.
9. Marcantonio SM, Fechner PY, Migeon CJ, et al. Embryonic testicular regression sequence: a part of the clinical spectrum of 46,XY gonadal dysgenesis. Am J Med Genet 1994;49: 1–5.
10. Smith NM, Byard RW, Bourne AJ. Testicular regression syndrome-a pathological study of 77 cases. Histopathology 1991;19: 269–272.
11. Zenaty D, Dijoud F, Morel Y, et al. Bilateral anorchia in infancy: occurrence of microphallus and the effect of testosterone treatment. J Pediatr. 2006;149: 687–691.
12. Brauner R, Neve M, Allali S, et al. Clinical, Biological and Genetic Analysis of anorchia in 26 boys. PLoS One. 2011;6(8):e23292.
13. Lodh B, Kanwar V, Kaku Singh AK, Singh SR. Unfused crossed renal ectopia with ipsilateral anorchia- a rare entity. J. Clin. Diagn Res. 2013 Sep; 7(9): 2029-2030
14. Bernasconi S, Ghizzoni L, Panza C, Volta C, et al. Congenital anorchia: natural history and treatment. Horm.Res. 1992;37: 50-54.
15. Bablok L, Janczewski Z, Czaplicki M, Kwiatkowska Z.Plasma testosterone levels before and after stimulation with HCG in anorchism. Int Urol Nephrol. 1979;11: 57-60.
16. Jarow NP, Berkowitz GD, Migeon CJ, et al. Elevation of serum gonadotropins establishes the diagnosis of anorchism in prepubertal boys with bilateral cryptorchidism. J Urol. 1986;136: 277- 279
17. De Rosa M, Lupoli G, Mennitti M, Zarrilli S, et al. Congenital bilateral anorchia: clinical, hormonal and imaging study in 12 cases. Andrologica. 1996; 28 (5): 281-285
18. Rousso I, Illiopoulos F, Athanasiadou F, et al. Congenital bilateral anorchia: hormonal, molecular and imaging study of a case. Genetics and Molecular Research.642 Genetics and Molecular Research.2006 Oct 31;5(4):638-42
19. Belgorosky A, Rivarola MA. Sex hormone-binding globulin response to human chorionic gonadotropin stimulation in children with cryptorchidism, anorchia, male pseudohermaphroditism, and micropenis. J Clin Endocrinol Metab. 1982;54: 698-704.