title: Cellular atypia in a rheumatoid nodule: a diagnostic pitfall of aspiration biopsy.
abstract: A 63-year-old cachectic white male developed subcutaneous scalp nodules. Clinically these were felt most likely to represent metastatic tumor, although the patient was known to have rheumatoid arthritis. Aspiration cytology was interpreted as malignant due to the presence of atypical cells, but tissue biopsies demonstrated necrotizing palisading granulomas. The diagnostic hazard of cellular atypia in rheumatoid nodules is discussed.
mesh_terms: D001707:Biopsy, Needle; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D006801:Humans; D008297:Male; D008875:Middle Aged; D012218:Rheumatoid Nodule / Q000473:pathology*; D012535:Scalp; D012536:Scalp Dermatoses / Q000473:pathology*; D012878:Skin Neoplasms / Q000473:pathology* / Q000556:secondary