AIM: Rachiphagus is a rare congenital anomaly in which conjoined twins are fused at the midline of the vertebral column region. When one twin is malformed, the condition is referred to as a parasitic twin. The term "parasitic twin" also encompasses cases involving extra limbs or limb-like structures. Despite ongoing research, the underlying causes of this condition remain unknown.

MATERIAL and METHODS: This is a systematic review of the literature with a case report. A literature search was done in English language in PubMed and Semantic-Scholar from 1952 to 2023. All articles and cases with excess leg or mass which were attached at the back of the spine were reviewed and analysed.

RESULTS: A total of 65 cases with rachipagus anomaly were included in this study. Females 37 (56.9%) were affected more than males 28 (43.1%). The lower limbs were in 41 (63.1%) cases, followed by rudimental limbs and mass were in 15 (23.1%) cases, upper limbs were in 8 (12.3%) cases and rudimental upper and low limbs were in 1 (1.5%) case. In majority of cases, accessory limb or mass were attached at lumbosacral region, 27 (41.5%), followed by 12 (18.5%) cases at lumbar region, 7 (10.8%) were at thoracolumbar region, 5 (7.7%) were at sacral and other regions. More than half of the cases 34 (52%) were in Asian countries, followed by 24 (37%) cases in Africa.

CONCLUSION: Rachipagus parasitic twin is congenital abnormalities that develops during embryogenesis and exists at birth with structural deformities of the spine and additional limb or limb like mass. This article presents a novel rachipagus case and systematically reviews the relevant literature.