Fine needle aspiration cytology of subareolar abscess of the breast. Spectrum of cytomorphologic findings and potential diagnostic pitfalls.

The cytomorphologic findings of eight cases of subareolar abscess of the breast diagnosed by fine needle aspiration (FNA) biopsy are presented. A spectrum of cytologic findings was appreciated, including diagnostic anucleated squames associated with numerous neutrophils, keratinous debris, cholesterol crystals, parakeratosis and strips of squamous epithelium. A foreign-body reaction, with sheets of histiocytes and multinucleated foreign-body-type giant cells, was noted in some of the cases. Potential pitfalls for a false-positive diagnosis of malignancy included the presence of groups of atypical ductal cells, squamous atypia and fragments of exuberant granulation tissue. Seven of the eight cases had complete surgical excision of the lesion, which demonstrated the characteristic findings of dilated lactiferous ducts undergoing squamous metaplasia with rupture and surrounding extensive acute and chronic inflammation with foreign-body reaction. With recognition of the FNA cytologic findings of subareolar abscess of the breast, a specific diagnosis can be rendered, which then allows different treatment modalities depending on the stage of the lesion. Appreciation of the spectrum of cytologic features will enable the pathologist to make the correct diagnosis and thereby avoid potential pitfalls that can possibly lead to a false-positive diagnosis of malignancy.