Axillary arch (of Langer): A large-scale dissection and simulation study based on unembalmed cadavers of body donors

Prevalence of Axillary Arch Variant Anatomy on Breast MRI and Impact on Axillary Lymph Node Assessment

OBJECTIVE

To assess the prevalence of the axillary arch (AA) variant and its impact on the sensitivity of US vs MRI for detecting axillary nodal metastases in patients with breast cancer.

METHODS

The IRB waved informed consent for this retrospective study. Three hundred, eighty-two breast MRIs performed for the extent of disease of breast cancer between 2012 and 2023 were reviewed for the presence of AA. Pre-MRI axillary US was available in 322 of these cases. The presence of axillary adenopathy was documented and correlated with pathology. A paired sample comparison was used to calculate sensitivities of US and MRI for detection of the AA.

RESULTS

The AA was detected on breast MRI in 6.8% (26/382) of patients. Of these, 30.8% (8/26) were bilateral, 50% (13/26) were unilateral left, and 19.2% (5/26) were unilateral right. All had lymph nodes both superficial and deep to the AA. Of the 26 patients with AA, 19 patients underwent pre-MRI axillary US. Biopsy-proven malignant adenopathy was detected on MRI but missed on US in 10.5% (2/19) of patients with AA but only 2.5% (7/279) of patients without AA. Sensitivity for detection of lymphadenopathy on MRI and US was 69.7% (82/122)% and 67.5% (77/114) for all patients (P = .17), 72.2% (78/108) and 68.5% (74/108) for patients without AA (P = .21), and 66.2% (4/6) and 50.0% (3/6) for patients with AA. The small sample size of patients with AA precluded statistical comparison.

CONCLUSION

The AA is a common variant detectable on breast MRI. Axillary nodal metastases may reduce US sensitivity for identifying nodal metastases. Further investigation is required to establish statistical significance.

An Intraoperative Encounter With Langer's Axillary Arch and Its Clinical Significance

Langer's axillary arch (LAA) is the most common accessory muscle encountered during axillary surgery. We present a 55-year-old lady who underwent a right wide local excision and sentinel lymph node biopsy. Intraoperatively, we identified an aberrant muscle slip traversing the axilla, anterior to the neurovascular structures. It originated from the latissimus dorsi muscle and inserted into the pectoralis major. This report explores the current knowledge of LAA and discusses the importance of recognising it intraoperatively in the era of minimisation of axillary surgery. Implications of failing to recognise it include suboptimal regional control, compromised oncological treatment, or neurovascular injuries.

Real-World Evidence of Langer's Axillary Arch: Bridging Anatomical Variations and Surgical Practice for Safer Axillary Procedures

Langer's axillary arch is an anatomical variant characterized by a fibromuscular band extending from the latissimus dorsi to the pectoralis major, humerus, or coracoid process, traversing the axillary region. This structure may alter expected anatomical relationships and has the potential to compress neurovascular elements, thereby complicating surgical procedures. Although extensively described in cadaveric studies, in vivo identification during surgery remains infrequently reported. Given its anatomical variability and potential impact on surgical outcomes, further intraoperative documentation of this variant is clinically relevant and may contribute to improved surgical safety and planning. We present the case of a 65-year-old female with left axillary lymph node metastases from melanoma, undergoing complete axillary lymphadenectomy. Intraoperatively, a fibromuscular structure consistent with Langer's axillary arch was identified, extending from the latissimus dorsi and crossing the neurovascular bundle before inserting on the humerus. Careful dissection was performed to preserve vital structures and ensure oncologic completeness. The lymphadenectomy was successfully completed with histologically clear margins. The patient tolerated surgery well, received adjuvant immunotherapy, and remains disease-free after one year of follow-up. The recognition of Langer's axillary arch during the procedure was critical in preventing inadvertent vascular or nerve injury, ensuring a safe and effective intervention. By bridging anatomical research with clinical practice, this case underscores the clinical importance of anatomy during surgical procedures in the axilla. Failure to recognize Langer's axillary arch can increase the risk of surgical complications, including neurovascular injury or incomplete dissections. The in vivo documentation of this structure provides a valuable educational reference for surgeons, emphasizing the relevance of detailed anatomical understanding in improving patient outcomes.

Axillary arch muscle and pectoralis quartus: an unusual combination of two variant supernumerary muscles in the axillary region - a case report

Variant anatomy in the axillary region is of great clinical significance. It is one of the most frequently accessed regions for radical dissection surgery. During routine dissection of embalmed cadavers, we found a rare case of two accessory muscular slips emerging from the lateral border of latissimus dorsi (LD) and the inferolateral border of pectoralis major (PM), crossing the neurovascular structures in the axilla and merging distally together to the brachial fascia at the upper end of humerus below the bicipital groove. The accessory slip from LD is commonly referred to as the "axillary arch" in literature. We identified the accessory slip from the PM crossing over the axilla as pectoralis quartus. These aberrant slips can cause neurovascular compression in the axilla and can have clinical implications. Prior knowledge of the variant anatomy is the key to successful surgery in the axilla, thereby avoiding inadvertent injuries and post-operative complications.

What is the axillary arch (of Langer)?

We read with great interest the article by Weninger et al. (2023) on the presence of the axillary arch (AA) (of Langer) found during anatomical dissections-"Axillary arch (of Langer): A large-scale dissection and simulation study based on unembalmed cadavers of body donors." The authors performed their study using 400 axillae from 200 unembalmed cadavers; they identified this variant muscle in 27 axillae of 18 cadavers. Weninger et al. (2023) described the muscular AA in 15 cases; AA was composed of connective tissue in six cases, and AA comprised muscular and connective tissue in six cadavers. Moreover, these authors indicated that after passive abduction and lateral rotation of the arm, 17 arches (63%) came into contact with the neurovascular axillary bundle, which is of clinical importance. In our opinion, this is the most precise and detailed AA muscle study in the literature, illustrated with excellent photographs and schemes. Such studies expand the existing data in the literature and are of real help to clinicians. However, we want to present our modest comments about the title of the article and would like to pose the question, "What is the axillary arch (of Langer)?" Weninger et al. (2023) stated that connective or muscular tissue crossing the axilla is termed the AA (of Langer). This structure splits from the latissimus dorsi muscle, crosses the axilla, and joins the anterior part of the upper limb. The first detailed description of this variation was published in 1846 by Karl Langer Ritter von Edenberg (Langer, 1846). Nowadays, a significant number of articles term all muscular and fibromuscular connections between the latissimus dorsi muscle and the anterior part of the upper limb as "Langers AA" (Markou et al., 2023; Sang et al., 2019; Scrimgeour et al., 2020; Taterra et al., 2019). What Langer described in his work "Zur anatomie des musculus latissimus dorsi" was a fibrous thickening of the medial edge of the axillary fascia between the borders of the pectoralis major and the latissimus dorsi muscles, a structure he termed "Achselbogen." In a sequel of this article, Langer investigated muscular fibers inserting at or encircling the connective tissue "Achselbogen" (Langer, 1846). Therefore, in our opinion, in the study of Weninger et al. (2023), the term AA (of Langer) should only be used to describe the cases presenting solely with a connective tissue "arch" or these comprised of both, muscular and connective tissue. Weninger et al. (2023) noted that muscle fibers could not be excluded in these cases. Of course, to answer this question accurately, a histological study of these cases would be necessary.