Incomplete duplication of a lower extremity (polymelia): a case report
Journal of Medical Case Reports volume 8, Article number: 184 (2014)
Polymelia, or congenital duplication of a limb, is an extremely rare entity in humans, with few cases reported in the literature.
We present the case of a six-month-old Hispanic boy born with a lower limb bud on the left posterior thigh.
The infant had a favorable outcome and evolution after surgical treatment of his supernumerary limb, with no after-effects or impairment whatsoever.
Our case report concerns a six-month-old Hispanic first-born son of young, nonconsanguineous parents with no family history of hereditary diseases or major dysmorphology. The pregnancy passed without major complications and with no accidental or work-related exposure to genotoxic agents.The infant was born at term with normal anthropometry and no complications or major dysmorphic features except a limb bud, which was located on the posterointernal face of the left thigh (Figure 1).The undeveloped limb was surgically removed, and the 11-cm-long specimen was sent to the Pathology Service. The surgically removed end was bloody and had an exposed bone segment. There were three digitiform formations at the opposite end, two of which were joined together in a tweezer-like configuration. A kink with limited movement and covered with skin and abundant adipose tussue was observed in the central part (Figure 2). The surgical specimen was formalin fixed and paraffin embedded, cut at 4μm and subsequently stained with hematoxylin and eosin.The histopathological diagnosis was incomplete congenital duplication of the left lower extremity (polymelia). Histological analysis revealed diaphyseal endochondral ossification and cartilaginous epiphyseal plates maturing in accordance with the infant’s age (Figures 3, 4 and 5).
Limb development involves a very large number of genes . One gene widely associated with the development of supernumerary limbs is the mouse mutant disorganization Ds gene [OMIM:223200] [9, 14], which is a semidominant gene with variable penetrance in heterozygotes and lethality in homozygotes; 67% of heterozygotes have multiple defects and the rest have single defects, in which polymelia is prominent .
Limb development is a very complex process involving precise gene regulation fundamental to normal growth . Findings in animal models have explained a great deal about these functions and have improved our understanding of the etiopathogeny of malformations, but more research is necessary to extend knowledge of these delicate processes. Surgical resection of the accessory limb at an early age is recommended in patients with supernumerary extremities [12, 15].
In our present case, the infant had a favorable outcome and evolution subsequent to surgical treatment of his supernumerary limb, with no sequelae or disability whatsoever to date.
Written informed consent was obtained from the patient’s legal guardian(s) for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
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The authors thank Cesar Vaca (technologist) for his valuable technical support.
The authors declare that they have no competing interests.
NM performed the histological examination and diagnosis of the patient. LR and VE conducted a thorough literature review of duplication of the limbs in the human tract and were the major contributors to the writing of the manuscript. All authors read and approved the final manuscript.
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Montalvo, N., Redrobán, L. & Espín, V.H. Incomplete duplication of a lower extremity (polymelia): a case report. J Med Case Reports 8, 184 (2014). https://doi.org/10.1186/1752-1947-8-184