Appendix muscle bands, a forgotten entity

Appendix muscle bands (AMB) develop from the appendix muscle layer into the mesoappendix. There are few recent publications on this forgotten entity. The objectives of this study were to assess the morphological features of AMB as detected at microscopy examination of appendectomy specimens.

Sixty-six cases of AMB as detected on appendectomy specimens were assessed for microscopy features on routine hematoxilin and eosin stained tissue slides. The morphological features were analyzed with regard to the main clinico-pathological parameters.

AMBs were multiple in 35 cases. Most AMBs were located between the tip and cecal limit, 7 at the tip, and 1 at the cecal limit of the appendectomy specimen. Associated appendix lesions were: acute appendicitis, neuroma, mesoappendix cyst, muscle hiatus, and diverticulae (60,6,2,45, and 1, respectively). In 24 appendices, the AMB developed from the perihiatus muscle. Two microscopy types of AMBs were detected: muscle-AMB and mesoappendix-AMB.

AMB may be detected incidentally at microscopy of appendectomy specimens. Acute appendicitis was associated in most cases, independently on the microscopy type of AMB. Appendix abnormalities as neuroma, mesoappendix cyst, muscle hiatus, and diverticulae can be associated to AMBs.