A 35-year-old female, G2P1L1, underwent an antenatal scan at 36 weeks. Large thoraco-lumbar neural tube defect and Arnold-Chiari malformation type II were detected in the fetus. A female fetus weighing two kg was delivered following induction for termination of pregnancy. Autopsy confirmed Arnold-Chiari malformation, and meningomyelocele at thoraco-lumbar region. Histology showed features suggestive of amniotic fluid aspiration in non-aerated lungs. A transverse band of tissue across the midline was noted above the kidneys, posterior to aorta. No separate adrenals were identified in superior poles of kidney (Figure 1A, B). Histologic examination of transverse band of tissue showed a capsulated tissue with cells displayed in zonal pattern. A compact cellular layer formed outer layer, columns of paler cells in the middle and smaller cells in cords on inner side consistent with adrenal gland morphology (Figure 2). This confirmed the diagnosis of adrenal fusion anomaly.

Adrenal gland agenesis, hypoplasia and accessory gland are common congenital anomalies of adrenal glands. While fusion anomalies of kidney are relatively common (1 in 300 pediatric autopsies), congenital fusion of adrenal glands is a rare anomaly with only 65 cases reported in literature. [1] [2] Most of them are detected at autopsy [1] and few as an incidental finding in imaging studies associated with other anomalies. [1] [2] These anomalies are functionally normal. [2] The fusion occurs across the midline, with resultant horseshoe or butterfly shaped gland. Fusion can be preaortic or postaortic. [1] [2] Normal histology of fused glands implies that the defect in embryogenesis occurs probably at 5–7th week. Similar case reports confirm the constant association with midline central nervous system defects such as meningomyelocele and Arnold-Chiari malformation. This confers the postulation that adrenal glands develop from single primordial gland rather than separate right and left glands. Horseshoe adrenal is less common component of asplenia syndrome, a form of heterotaxy characterized by bilateral right-sidedness. Adrenal fusion may be considered as a differentiating feature between asplenia and polysplenia. [3] The management of such cases depends on type and severity of associated anomalies, their response to surgical intervention [2] and was detected antenatally which ends in termination as in our case. The occurrence of this anomaly in successive pregnancies is not mentioned in literature.

Congenital fusion of adrenal gland can be an incidental radiological finding. Awareness of this rare entity can avoid unnecessary interventions since they are histologically and functionally normal and no intervention is required but screening for potential assosciated anomalies such as central nervous system malformations, renal agenesis, asplenia, anomalies of the internal genitalia and complex cardiac anomalies are warranted.

1. Klatt EC, Pysher TJ, Pavlova Z. Adrenal fusion. Paediatric and Developmental Pathology 1998;1(6):475–9.   [CrossRef]   [Pubmed]    
2. De Visschere P, Schollaert E, Villeirs G. Adrenal gland fusion. JBR-BTR 2011;94(2):89.   [Pubmed]    
3. Strouse PJ, Haller JO, Berdon WE, Rosovsky MA, Bellah RD, Barr Jr M. Horeshoe adrenal gland in association with asplenia: presentation of six new cases and review of literature. Paediatr Radiol 2002;32(11):778–2.   [CrossRef]   [Pubmed]