title: Atypical squamous metaplasia of seromas in breast needle aspirates from irradiated lumpectomy sites: a potential pitfall for false-positive diagnoses of carcinoma.
abstract: The presence of squamous metaplasic cells is an uncommon finding in fine-needle aspiration (FNA) biopsies of the breast. We report that FNA smears containing atypical squamous metaplastic cells derived from the lining of seroma-type cavities following lumpectomy and irradiation in patients with breast cancer can be a potential pitfall for a false-positive diagnosis of recurrent malignancy. Four fine-needle breast aspirates from two adult patients with previous histories of invasive breast carcinoma were retrieved. One specimen was from a 56-yr-old female, while the remaining three FNAs aspirates were from a 75-yr-old female. Both patients presented with indurated cystic lesions arising at irradiated lumpectomy sites. The cytospins from the 56-yr-old patient showed markedly atypical cells having enlarged, degenerating, hyperchromatic nuclei and surrounding dense cytoplasm with sharp borders that were suspicious for carcinoma. A mastectomy revealed irradiation changes and atypical squamous metaplastic cells lining a cystic cavity consistent with a seroma, but there was no evidence of residual cancer. After three aspirations yielded "atypical" diagnoses, the second patient underwent core needle biopsies that also revealed changes consistent with a seroma cavity lined by atypical squamous metaplastic cells. We believe this is the first report of squamous metaplasia occurring in a seroma cavity following lumpectomy and irradiation of the breast. The squamous metaplastic cells in aspirates of these cystic lesions may display significant cellular atypia that can potentially result in a false-positive diagnosis of malignancy.
authors.affiliation: Allegheny General Hospital, MCP/Hahnemann University, Pittsburgh, PA 13212, USA.
authors.forename: Reda S
authors.initials: RS
authors.lastname: Saad
authors.forename: Jan F
authors.initials: JF
authors.lastname: Silverman
authors.forename: Thomas
authors.initials: T
authors.lastname: Julian
authors.forename: Karen M
authors.initials: KM
authors.lastname: Clary
authors.forename: Charles D
authors.initials: CD
authors.lastname: Sturgis
mesh_terms: D000368:Aged; D001707:Biopsy, Needle; D001940:Breast / Q000473:pathology* / Q000601:surgery; D001943:Breast Neoplasms / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery; D002294:Carcinoma, Squamous Cell / Q000473:pathology*; D003937:Diagnosis, Differential; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D015412:Mastectomy, Segmental; D008679:Metaplasia / Q000473:pathology; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology; D011832:Radiation Injuries; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects*