Category IV: Neoplastic (Benign)

Abstract

The Papanicolaou Society of Cytopathology recommendations for respiratory cytology utilize a neoplastic category that contains both clearly benign neoplasms and neoplasms with a low but undetermined malignant potential. Assignment to the neoplastic category requires that sufficient morphologic features are present to definitively define a smear as representative of a specific benign neoplasm. Neoplasms with low malignant potential and some low-grade carcinomas overlap morphologically and are cytologically difficult to separate. Clearly malignant neoplasms including a variety of well-differentiated adenocarcinomas and low-grade sarcomas morphologically overlap entities with low malignant potential. Thus, separation of the neoplastic category into two subcategories has importance for cytologic evaluation, differential diagnosis, and assessment of malignancy risk. This subdivision of the neoplastic category into those lesions which are clearly benign and those that have a low risk for recurrence or metastasis is clinically useful. This categorization allows the treating physician discretion in his or her therapeutic approach to a patient. Lesions of low or undetermined malignant risk in a young, healthy individual are often resected, while a similar neoplasm in an elderly infirm individual may receive only observational or medical therapy.

The category neoplastic, benign neoplasm includes neoplastic lesions in which the cytologic specimen is sufficiently cellular and represented to be diagnostic of a specific benign neoplasm. Assignment to this category may be facilitated by both clinical and imaging findings as well as some ancillary testing including immunocytochemistry. Neoplasms included in the neoplastic, benign category include pulmonary hamartoma, squamous papilloma, granular cell tumor, hemangioma, and sclerosing pneumocytoma. It is important to remember that carcinoid tumors are considered malignant and appropriately assigned to the malignant or suspicious for malignancy categories rather than the neoplasm category.