Accessory limbs associated with spina bifida - a second look

Abstract

An accessory limb associated with spina bifida was already reported by the authors. We had then described it as a result of a very early splitting of the limb bud arising from the paraxial mesoderm. We have subsequently seen three other such cases, which are described in this report as well as a review of five other cases in the literature. It is proposed that the growth of the accessory limb occurs from a mesodermal blastema that is a result of de-differentiation from Schwann cells.

Complex Spinal Dysraphism with Multiple Anomalies

“…Krishna and Lal [6], in their series of 9 cases, supported the hypotheses of Gardner [7] and Egar [8]. Gardner [7] differentiated between primary and secondary neural-tube defects and suggested that while the former resulted from failure of the neural tube to close, the latter resulted from its rupture after closure due to oversecretion of neural tube fluid.…”

Lumbosacral parasitic rachipagus twin

“…All were located at or near the dorsal midline. A review of the literature reveals another 7 cases [3,[6][7][8][9]. Of the 28 cases reported so far, including our patient, 17 were females and 5 were males, and in 5 cases, the sex was not reported.…”

“…The presence within the parasitic mass of polymorphic tissues, as well as organs and tissues belonging to several organ systems, would appear to support the theory of Spencer [4] that these lesions represent aborted or parasitic twinning . Significantly, Chadha et al [10] and Sharma et al [11] reported the presence of a benign teratoma within the parasitic mass, whereas a lipomatous mass was present within the parasite in other reported cases [6,9]. This indicates that, as has previously been suggested, there is a thin line of demarcation between teratomata, aborted duplications, fetal inclusions, more developed forms of parasitic twinning, and conjoined twins [10].…”

“…By and large, an upper limb and its girdle bones are usually seen when the parasitic union is in the cervical or upper thoracic regions, whereas a lower limb and the associated girdle bones predominate in cases of union lower down in the dorsal and lumbar regions [9]. Table 1 shows the clinical details and surgical findings in the previously reported cases of parasitic rachipagus twinning [3,4,[6][7][8][9][10][11]. The presence within the parasitic mass of polymorphic tissues, as well as organs and tissues belonging to several organ systems, would appear to support the theory of Spencer [4] that these lesions represent aborted or parasitic twinning .…”

“…Such hemangiomatous lesions in the overlying skin, small appendages, and dimpling of the skin are characteristic of spina bifida occulta. In cases of occult spinal dysraphism, cartilaginous pieces and bony spicules are often encountered in the lipomatous mass [6]. Ectopic metanephric tissue has also been seen in association with diastematomyelia [12] and with a lumbosacral lipoma with intradural extension [13].…”