Axilla is a pyramidal-in-shape "virtual cavity" housing multiple anatomical structures and connecting the upper limb with the trunk. To the best of our knowledge, in the pertinent literature, a detailed sonographic protocol to comprehensively assess the axillary region in daily practice is lacking. In this sense, the authors have briefly described the anatomical architecture of the axilla-also using cadaveric specimens-to propose a layer-by-layer sonographic approach to this challenging district. The most common sonographic pathological findings-for each and every anatomical compartment of the axilla-have been accurately reported and compared with the corresponding histopathological features. This ultrasound approach could be considered a ready-to-use educational guidance for the assessment of the axillary region. CRITICAL RELEVANCE STATEMENT: Axilla is a pyramidal-in-shape "virtual cavity" housing multiple anatomical structures and connecting the upper limb with the trunk. The aim of this review article was to describe the anatomical architecture of the axilla, also using cadaveric specimens, in order to propose a layer-by-layer sonographic approach to this challenging district.

1st Faculty of Medicine Institute of Anatomy Charles University Prague Czech Republic

Clinic of Infectious Diseases Department of Medicine and Science of Aging G d'Annunzio University Chieti Italy

Department Life and Health 5 Tiberio Università Degli Studi del Molise Campobasso Italy

Department of Experimental Diagnostic and Specialty Medicine University of Bologna Bologna Italy

Department of Innovative Technologies in Medicine and Dentistry University G d'Annunzio Chieti Italy

Department of Neuroscience Imaging and Clinical Sciences G d'Annunzio University Chieti Italy

Department of Radiology Istituto Diagnostico Varelli Naples Italy

Department of Radiology Oncology Anatomo Pathology Sapienza University of Rome Rome Italy

Internal Medicine Bentivoglio Hospital AUSL Bologna Bentivoglio Italy

Movement Sciences and Wellbeing Department University of Naples Parthenope Naples Italy

Ospedale S Spirito Università Degli Studi Chieti Pescara Chieti Italy

Physical and Rehabilitation Medicine Unit Luigi Sacco University Hospital ASST Fatebenefratelli Sacco Milan Italy

Unit of Radiology Santissima Annunziata Hospital Chieti Italy

Unit of Ultrasound in Internal Medicine Department of Medicine and Science of Aging G d'Annunzio University Chieti Italy

See more in PubMed

Ricci V, Ricci C, Gervasoni F, et al. From histo-anatomy to sonography in myofascial pain syndrome: EURO-MUSCULUS/USPRM approach. Am J Phys Med Rehabil. 2022 doi: 10.1097/PHM.0000000000001975. PubMed DOI

Bianchi S, Martinoli C, Abdelwahab IF. Ultrasound of tendon tears. Part 1: general considerations and upper extremity. Skeletal Radiol. 2005;34(9):500–512. doi: 10.1007/s00256-005-0956-1. PubMed DOI

Ricci V, Ricci C, Cocco G, et al. Histopathology and high-resolution ultrasound imaging for peripheral nerve (injuries) J Neurol. 2022 doi: 10.1007/s00415-022-10988-1. PubMed DOI

Ricci V, Ricci C, Gervasoni F, et al. From histo-anatomy to sonography in lymphedema: EURO-MUSCULUS/USPRM approach. Eur J Phys Rehabil Med. 2022;58(1):108–117. doi: 10.23736/S1973-9087.21.06853-2. PubMed DOI PMC

Wu WT, Chang KV, Lin CP, et al (2022) Ultrasound imaging for inguinal hernia: a pictorial review. Ultrasonography 10.14366/usg.21192. PubMed PMC

Morley N, Grant T, Blount K, et al. Sonographic evaluation of athletic pubalgia. Skeletal Radiol. 2016;45(5):689–699. doi: 10.1007/s00256-016-2340-8. PubMed DOI

Balconi G. US in pubalgia. J Ultrasound. 2011;14(3):157–166. doi: 10.1016/j.jus.2011.06.005. PubMed DOI PMC

McMinn RMH (1994) Last’s anatomy regional and applied. 9th ed. Edinburgh: Churchill Livingstone 63–70.

Khan A, Chakravorty A, Gui GP. In vivo study of the surgical anatomy of the axilla. Br J Surg. 2012;99(6):871–877. doi: 10.1002/bjs.8737. PubMed DOI

Feng SH, Hsiao MY, Wu CH, et al. Ultrasound-guided diagnosis and management for quadrilateral space syndrome. Pain Med. 2017;18(1):184–186. doi: 10.1093/pm/pnw256. PubMed DOI

Chen H, Onishi K, Zhao X, et al. Neuromuscular ultrasound application to the electrodiagnostic evaluation of quadrilateral space syndrome. PM R. 2014;6(9):845–848. doi: 10.1016/j.pmrj.2014.01.017. PubMed DOI

DeFilippis EM, Arleo EK. The ABCs of accessory breast tissue: basic information every radiologist should know. AJR Am J Roentgenol. 2014;202(5):1157–1162. doi: 10.2214/AJR.13.10930. PubMed DOI

Ricci V, Abdulsalam AJ, Özçakar L. Ultrasound Imaging for dummies: getting oriented among the planes. J Rehabil Med. 2019;51(8):624–625. doi: 10.2340/16501977-2581. PubMed DOI

Dialani V, James DF, Slanetz PJ. A practical approach to imaging the axilla. Insights Imaging. 2015;6(2):217–229. doi: 10.1007/s13244-014-0367-8. PubMed DOI PMC

Ricci V, Ricci C, Cocco G, et al. From histology to sonography in skin and superficial tissue disorders: EURO-MUSCULUS/USPRM* approach. Pathol Res Pract. 2022;237:154003. doi: 10.1016/j.prp.2022.154003. PubMed DOI

Marchal G, Oyen R, Verschakelen J, et al. Sonographic appearance of normal lymph nodes. J Ultrasound Med. 1985;4(8):417–419. doi: 10.7863/jum.1985.4.8.417. PubMed DOI

Michelin P, Delarue Y, Duparc F, et al. Thickening of the inferior glenohumeral capsule: an ultrasound sign for shoulder capsular contracture. Eur Radiol. 2013;23(10):2802–2806. doi: 10.1007/s00330-013-2874-2. PubMed DOI

Wu WT, Chang KV, Hsu YC, et al. Artifacts in musculoskeletal ultrasonography: from physics to clinics. Diagnostics (Basel) 2020;10(9):645. doi: 10.3390/diagnostics10090645.PMID:32867385;PMCID:PMC7555047. PubMed DOI PMC

Wortsman X. Top advances in dermatologic ultrasound. J Ultrasound Med. 2022 doi: 10.1002/jum.16000. PubMed DOI

Jin W, Ryu KN, Kim GY, et al. Sonographic findings of ruptured epidermal inclusion cysts in superficial soft tissue: emphasis on shapes, pericystic changes, and pericystic vascularity. J Ultrasound Med. 2008;27(2):171–176. doi: 10.7863/jum.2008.27.2.171. PubMed DOI

Jemec GB. Clinical practice Hidradenitis suppurativa. N Engl J Med. 2012;366(2):158–164. doi: 10.1056/NEJMcp1014163. PubMed DOI

Wortsman X, Moreno C, Soto R, et al. Ultrasound in-depth characterization and staging of hidradenitis suppurativa. Dermatol Surg. 2013;39(12):1835–1842. doi: 10.1111/dsu.12329. PubMed DOI

Grand D, Frew JW, Navrazhina K, et al. Doppler ultrasound-based noninvasive biomarkers in hidradenitis suppurativa: evaluation of analytical and clinical validity. Br J Dermatol. 2021;184(4):688–696. doi: 10.1111/bjd.19343. PubMed DOI PMC

Kligman AM, Strauss JS. Pseudofolliculitis of the beard. AMA Arch Derm. 1956;74(5):533–542. doi: 10.1001/archderm.1956.01550110077016. PubMed DOI

Jasterzbski TJ, Schwartz RA. Pseudofolliculitis cutis: a vexing disorder of hair growth. Br J Dermatol. 2015;172(4):878–884. doi: 10.1111/bjd.13427. PubMed DOI

Crisan D, Wortsman X, Alfageme F, et al. Ultrasonography in dermatologic surgery: revealing the unseen for improved surgical planning. J Dtsch Dermatol Ges. 2022 doi: 10.1111/ddg.14781. PubMed DOI

Ricci V, Ricci C, Gervasoni F, et al. From physical to ultrasound examination in lymphedema: a novel dynamic approach. J Ultrasound. 2022 doi: 10.1007/s40477-021-00633-4. PubMed DOI PMC

Lee BB, Villavicencio JL. Primary lymphoedema and lymphatic malformation: are they the two sides of the same coin? Eur J Vasc Endovasc Surg. 2010;39(5):646–653. doi: 10.1016/j.ejvs.2010.01.018. PubMed DOI

Moore JE, Jr, Bertram CD. Lymphatic system flows. Annu Rev Fluid Mech. 2018;50:459–482. doi: 10.1146/annurev-fluid-122316-045259.PMID:29713107;PMCID:PMC5922450. PubMed DOI PMC

Illman JE, Terra SB, Clapp AJ, et al. Granulomatous diseases of the breast and axilla: radiological findings with pathological correlation. Insights Imaging. 2018;9(1):59–71. doi: 10.1007/s13244-017-0587-9. PubMed DOI PMC

Ricci V, Ricci C, Tamborrini G, Chang KV, Mezian K, Zunica F, Naňka O, Kara M, Özçakar L. From histology to sonography in synovitis: EURO-MUSCULUS/USPRM approach. Pathol Res Pract. 2023;241:154273. doi: 10.1016/j.prp.2022.154273. PubMed DOI

Ying M, Ahuja A. Sonography of neck lymph nodes. Part I: normal lymph nodes. Clin Radiol. 2003;58(5):351–358. doi: 10.1016/s0009-9260(02)00584-6. PubMed DOI

Ahuja A, Ying M. Sonography of neck lymph nodes. Part II: abnormal lymph nodes. Clin Radiol. 2003;58(5):359–366. doi: 10.1016/s0009-9260(02)00585-8. PubMed DOI

Yang WT, Chang J, Metreweli C. Patients with breast cancer: differences in color doppler flow and gray-scale US features of benign and malignant axillary lymph nodes. Radiology. 2000;215(2):568–573. doi: 10.1148/radiology.215.2.r00ap20568. PubMed DOI

Cocco G, Delli Pizzi A, Taraschi AL, Boccatonda A, Corvino A, Ucciferri C, Falasca K, Caulo M, Vecchiet J. Atypical sites of lymphadenopathy after anti-COVID-19 vaccine: ultrasound features. Medicina (Kaunas) 2022;58(2):197. doi: 10.3390/medicina58020197.PMID:35208521;PMCID:PMC8878753. PubMed DOI PMC

Ariji Y, Kimura Y, Hayashi N, Onitsuka T, Yonetsu K, Hayashi K, Ariji E, Kobayashi T, Nakamura T. Power doppler sonography of cervical lymph nodes in patients with head and neck cancer. AJNR Am J Neuroradiol. 1998;19(2):303–307. PubMed PMC

Corvino A, Catalano F, Cipolletta Campanile A, et al. Interventional ultrasound in dermatology: a pictorial overview focusing on cutaneous melanoma patients. J Ultrasound Med. 2022 doi: 10.1002/jum.16073. PubMed DOI PMC

Walsh R, Kornguth PJ, Soo MS, Bentley R, DeLong DM. Axillary lymph nodes: mammographic, pathologic, and clinical correlation. AJR Am J Roentgenol. 1997;168(1):33–38. doi: 10.2214/ajr.168.1.8976915. PubMed DOI

Wojcinski S, Dupont J, Schmidt W, Cassel M, Hillemanns P. Real-time ultrasound elastography in 180 axillary lymph nodes: elasticity distribution in healthy lymph nodes and prediction of breast cancer metastases. BMC Med Imaging. 2012;19(12):35. doi: 10.1186/1471-2342-12-35.PMID:23253859;PMCID:PMC3536617. PubMed DOI PMC

Yu M, Liu Q, Song HP, Han ZH, Su HL, He GB, Zhou XD. Clinical application of contrast-enhanced ultrasonography in diagnosis of superficial lymphadenopathy. J Ultrasound Med. 2010;29(5):735–740. doi: 10.7863/jum.2010.29.5.735. PubMed DOI

Rubaltelli L, Khadivi Y, Tregnaghi A, Stramare R, Ferro F, Borsato S, Fiocco U, Adami F, Rossi CR. Evaluation of lymph node perfusion using continuous mode harmonic ultrasonography with a second-generation contrast agent. J Ultrasound Med. 2004;23(6):829–836. doi: 10.7863/jum.2004.23.6.829. PubMed DOI

Becciolini M, Galletti S, Vallone G, et al. Sonographic diagnosis of clinically unsuspected thrombosis of the medial marginal vein and dorsal arch of the foot. J Ultrasound. 2021;24(4):515–518. doi: 10.1007/s40477-019-00421-1. PubMed DOI PMC

Sajid MS, Ahmed N, Desai M, et al. Upper limb deep vein thrombosis: a literature review to streamline the protocol for management. Acta Haematol. 2007;118(1):10–18. doi: 10.1159/000101700. PubMed DOI

Lefebvre G, Le Corroller T. Ultrasound and MR imaging of peripheral nerve tumors: the state of the art. Skeletal Radiol. 2022 doi: 10.1007/s00256-022-04087-5. PubMed DOI

Tagliafico AS, Isaac A, Bignotti B, et al. Nerve tumors: what the MSK radiologist should know. Semin Musculoskelet Radiol. 2019;23(1):76–84. doi: 10.1055/s-0038-1676290. PubMed DOI

Stella SM, Gualtierotti R, Ciampi B, et al. Ultrasound features of adhesive capsulitis. Rheumatol Ther. 2022;9(2):481–495. doi: 10.1007/s40744-021-00413-w. PubMed DOI PMC

Chang KV, Lin CP, Lin CS, Wu WT, Özçakar L. A novel approach for ultrasound guided axillary nerve block: the inferior axilla technique. Med Ultrason. 2017;19(4):457–461. doi: 10.11152/mu-1232. PubMed DOI

Rashtak S, Gamble GL, Gibson LE, et al. From furuncle to axillary web syndrome: shedding light on histopathology and pathogenesis. Dermatology. 2012;224(2):110–114. doi: 10.1159/000337210. PubMed DOI

Mullen LA, Harvey SC. Review of axillary web syndrome: what the radiologist should know. Eur J Radiol. 2019;113:66–73. doi: 10.1016/j.ejrad.2019.02.001. PubMed DOI

Gupta A, Metcalf C, Taylor D. Review of axillary lesions, emphasising some distinctive imaging and pathology findings. J Med Imaging Radiat Oncol. 2017;61(5):571–581. doi: 10.1111/1754-9485.12579. PubMed DOI