Bilateral sternalis with unusual left-sided presentation: a clinical perspective

Area of Science:

• Anatomy
• Radiology
• Surgery

Background:

• The sternalis muscle is a common anterior chest wall variant, often superficial to the pectoralis major.
• Variations in sternalis muscle presentation can range from minimal fibers to a well-developed muscle.
• Anatomical anomalies like the sternalis muscle can present diagnostic challenges in clinical settings.

Purpose of the Study:

• To document and describe a rare bilateral sternalis muscle anomaly.
• To highlight the association of a large sternalis muscle with the absence of pectoralis major sternal fibers.
• To review the topography, development, and clinical implications of sternalis muscle variations.

Main Methods:

• Observation and detailed description of a bilateral sternalis muscle case.
• Documentation of the sternalis muscle's origin, insertion, and relationship to surrounding structures.
• Review of existing literature on sternalis muscle variations and their diagnostic implications.

Main Results:

• A bilateral sternalis muscle anomaly was identified.
• The left sternalis muscle was unusually large and bulky, accompanied by the absence of the sternal fibers of the pectoralis major.
• The sternalis muscles converged into an aponeurosis continuous with the sternocleidomastoid muscles.
• Potential for misinterpretation as a tumor on mammography and CT scans was noted.

Conclusions:

• This case presents a rare bilateral sternalis muscle variation with significant anatomical implications.
• The sternalis muscle anomaly can mimic pathologies, requiring careful radiological and surgical evaluation.
• Understanding such variations is crucial for accurate diagnosis and avoiding misinterpretation in medical imaging.