Gallbladder carcinoma: An attempt of WHO histological classification on fine needle aspiration material

Background: Carcinoma of the gallbladder (CaGB) is common in India and its prognosis depends primarily on the extent of the disease and histological type. We aim to study the role of guided fine needle aspiration cytology (FNAC) for diagnosis of CaGB and to evaluate the feasibility of applying world health organization (WHO) classification on fine needle aspiration (FNA) material to predict the outcome of the tumor. Materials and Methods: Retrospective cytomorphologic analysis was performed in all cases of CaGB diagnosed by ultrasound (US) guided FNAC over a period of 2 years. A specific subtype was assigned according to WHO classification based on characteristic cytologic features. These included papillary or acinar arrangement, intra and extracellular mucin, keratin, rosettes and columnar, signet ring, atypical squamous, small, clear, spindle and giant cells. Correlation with histopathology was performed when available. Results: A total of 541 aspirations with clinical or radiological suspicion of primary CaGB were studied. Of these, 54 aspirates were unsatisfactory. Fifty cases were negative for malignancy. Remaining 437 aspirates were positive for carcinoma. Histopathologic diagnosis was available in 32 cases. Adenocarcinoma was the most frequent diagnosis in 86.7% of cases. Mucinous, signet ring, adenosquamous, squamous, small cell, mixed adenoneuroendocrine and undifferentiated carcinoma including spindle and giant cell subtypes were diagnosed identifying specific features on FNAC. Correlation with histopathology was present in all, but one case giving rise to sensitivity of 96.8%. No post-FNA complications were recorded. Conclusions: US guided FNAC is a safe and effective method to diagnose CaGB. Although, rare, clinically and prognostically significant variants described in WHO classification can be detected on cytology.