Subpectoral abscess presents with erythema, induration of the pectoral region, and painful shoulder range of motion. This presentation most strongly suggests which diagnosis?

• A. Subpectoral abscess
• B. Axillary lymphadenitis
• C. Mastectomy scar infection
• D. Deltoid bursitis

Answer: (A)

Localized infection confined to the subpectoral space classically presents with erythema and firm induration over the pectoral region, often accompanied by pain with shoulder movement due to involvement of the pectoral girdle. That chest-wall localization is the clue that points to a subpectoral abscess. In contrast, axillary lymphadenitis would show tender lymph nodes in the axilla rather than an erythematous, indurated area on the chest wall. Mastectomy scar infection centers around the surgical scar itself, not the pectoral region. Deltoid bursitis causes lateral shoulder pain and tenderness over the deltoid with ROM limitation, without the distinct pectoral chest-wall findings.