Subclavius posticus muscle with anomalous posterior insertion: case report / Músculo subclavius posticus con inserción posterior anómala: reporte de un caso

SUMMARY: During routine anatomical dissection of the left supraclavicular and infraclavicular regions of a male cadaver, a supernumerary muscle was observed, which, by its position and insertions, consistent with the subclavius posticus muscle (posterior subclavius muscle). It had its anterior insertion by a thin tendon in the cranial surface of the first costal cartilage next to the subclavius muscle's insertion, and ran dorso-laterally crossing over the brachial plexus and subclavian vessels to end on the posterior surface of the serratus anterior muscle's fascia near to the superior margin of the scapula, without taking insertion on it, which differentiates it from the muscles described in the bibliography. This aberrant muscle has clinical implication since it has been described as a cause of thoracic outlet syndrome and it may appear in diagnostic imaging techniques simulating different pathological processes.

RESUMEN: Durante una disección de rutina de las regiones supraclavicular e infraclavicular izquierdas de un cadáver masculino, observamos un músculo supernumerario, el cual según su ubicación, origen e inserción, se corresponde con la descripción del músculo subclavius posticus (subclavio posterior). Presenta su inserción anterior mediante un delgado tendón en la cara superior del primer cartílago costal, a un lado de la inserción del músculo subclavio, y corre hacia posterior y lateral, cruzando por encima de los troncos del plexo braquial y los vasos subclavios para terminar en la superficie posterior de la fascia del músculo serrato anterior, cerca del margen superior de la escápula, sin prestar inserción en él, lo cual lo diferencia de los músculos descritos en la bibliografía. Este músculo tiene implicancia clínica debido a que ha sido descrito como causa del síndrome del estrecho superior torácico, y puede aparecer simulando procesos patológicos en estudios por imágenes.

Isolated plexiform neurofibroma mimicking a vascular lesion

Abstract Plexiform neurofibromas are benign tumors originating from peripheral nerve sheaths, generally associated with Neurofibromatosis Type 1 (NF1). They are diffuse, painful and sometimes locally invasive, generating cosmetic problems. This report discusses an adolescent patient who presented with an isolated, giant plexiform neurofibroma on her leg that was confused with a vascular lesion due to its clinical aspects. Once the diagnosis was confirmed by surgical biopsy, excision of the lesion was performed with improvement of the symptoms.