A unique anatomical variation of the lateral femoral cutaneous nerve arising from the ilioinguinal nerve: illustrative case.

Background: Ever since the first description of the condition meralgia paresthetica in 1878, there have been multiple studies on anatomical variations of the lateral femoral cutaneous nerve (LFCN). More than 200 publications are available in various databases. This nerve is of interest not only to nerve surgeons but also to laparoscopic surgeons, bariatric surgeons, general surgeons, orthopedists, and spine surgeons.

Observations: Here, the authors report one such variation of the LFCN, noticed during a cadaveric dissection pertaining to a didactic course. The authors noticed that the LFCN was coursing 6 cm lateral to the anterior superior iliac spine (ASIS), above the iliac crest to enter the anterolateral aspect of the thigh. On further dissection proximally, the LFCN originated from the ilioinguinal nerve.

Lessons: It is necessary for many surgeons to know these variations to avoid iatrogenic complications during procedures like open or laparoscopic hernia repair, laparoscopic port insertions, bone graft harvesting from the iliac crest, hip replacement surgeries via the anterior approach, and bariatric surgery. Although conventional teachings are that the LFCN is medial to the ASIS and enters the thigh below the inguinal ligament approximately within 2 cm of the ASIS, there are significant variations. To the authors' knowledge, the origin from the ilioinguinal nerve has not previously been reported. https://thejns.org/doi/10.3171/CASE24790.