Anaplastic Lymphoma Kinase (ALK)-Positive Anaplastic Large Cell Lymphoma Presenting as an Axillary Breast Abscess in a Young Woman: A Case Report

Malignant tumours - both lymphoid and epithelial - have been reported to present clinically and radiologically as abscesses, leading to significant diagnostic delays. Anaplastic large cell lymphoma (ALCL) is a rare subtype of T cell non-Hodgkin lymphoma (NHL) characterised by CD30 positivity and, in some cases, anaplastic lymphoma kinase (ALK) expression. Although nodal involvement is most common, extranodal or soft-tissue disease may present with abscess-like features, resulting in diagnostic delay. A 31-year-old woman presented with right axillary pain and swelling, initially diagnosed as an abscess. Despite multiple courses of antibiotics and repeat imaging, the lesion enlarged and became indurated. An initial biopsy showed only chronic inflammation. Surgical incision and drainage were later performed, and histopathological analysis of tissue fragments revealed atypical lymphoid proliferation. Immunohistochemistry confirmed CD30-positive, ALK-positive ALCL. Staging CT demonstrated a necrotic right axillary mass measuring 6 × 5.6 × 5.4 cm with splenomegaly (15 cm), but no mediastinal, retroperitoneal, or pelvic disease, as such findings were consistent with stage III(S) disease. The patient received brentuximab vedotin plus cyclophosphamide, doxorubicin and prednisone (BV-CHP) chemotherapy following multidisciplinary review and showed marked improvement. This case illustrates the diagnostic challenge of ALK-positive ALCL presenting as a recurrent axillary abscess. Early recognition and histopathological evaluation of atypical or non-resolving abscesses are essential for timely diagnosis and effective treatment, ultimately improving patient outcomes.