College of American Pathologists
Printable Version

  Fine-needle aspiration
  of pulmonary hamartoma





cap today

June 2005
PAP/NGC Programs Review

Michael Henry, MD

Fine-needle aspiration of the lung is a well-established method for the initial diagnosis of pulmonary nodules. While pulmonary hamartoma is a rare lesion, it is the most common benign neoplasm found in the lungs. The cytologic features of FNA of pulmonary hamartoma have been well described, but there is overlap between these lesions and certain well-differentiated pulmonary malignancies.

With this in mind, Jonathan Hughes, MD, PhD, and colleagues used the data from the CAP Interlaboratory Comparison Program in Nongynecologic Cytology to evaluate the accuracy of FNA biopsy in the diagnosis of pulmonary hamartoma (Arch Pathol Lab Med. 2005;129:19–22). These data provide a valuable resource of information regarding diagnostic accuracy for cytologists in a wide range of clinical practice settings. In this study, data from a six-year period were evaluated looking at the responses to a series of 19 cases of pulmonary hamartoma.

A total of 766 separate individual participant responses were received with a range of eight to 113 responses for each case. The participants chose the correct general category (benign) in 598 cases (78 percent). In only one case did all of the participants correctly classify the slide as benign. Of interest, in only 200 (26 percent) responses did the participants make the correct specific diagnosis of pulmonary hamartoma. An incorrect general diagnosis of malignant was made in 168 (22 percent) of the responses. The most common incorrect specific responses were carcinoid tumor, adenocarcinoma, and small cell carcinoma.

On review of the slides, all were found to have good cellularity, and the diagnostic features of pulmonary hamartoma were well represented, including cartilaginous/fibromyxoid stroma and numerous benign epithelial cells. The authors concluded that factors that may have contributed to the incorrect diagnosis of malignant included not recognizing the mesenchymal component on Papanicolaou stain (versus Diff-Quik) along with overcalling the often abundant epithelial elements.

Dr. Henry, a member of the CAP Cytopathology Committee, is staff pathologist at Cleveland Clinic Florida, Naples.