Contributed by Isil Z. Yildiz- Aktas, MD and Frank Schneider, MD
This 66-year-old female presented with an enlarging right middle lobe mass that had been incidentally found on a prior tuberculosis screen 6 years ago. The patient had been a lifelong nonsmoker. She had no pulmonary complaints. On physical exam, her neck was supple with no masses, no cervical or supraclavicular adenopathy was identified, her chest was clear to auscultation and percussion bilaterally, and heart rhythm was regular.
A computerized tomography (CT)-guided fine needle aspiration biopsy was performed and was nondiagnostic. However, given that this mass had been slowly increasing in size, it was recommended to resect the nodule now rather than at an older age when her health may not be as good.
A CT of the chest from 6 months before the resection showed a 3.2x2.5cm smoothly marginated pulmonary nodule in the medial segment right middle lobe that had increased in size from 2.1x1.7cm in comparison with the CT from 5 years earlier (Figure 1). The radiologist considered the findings suspicious for carcinoid tumor.
A repeat PET-CT (Positron emission tomography- Computed tomography) one month before the surgery again showed the unchanged intrinsic lung mass abutting the right border of the heart. The lungs were otherwise clear. No suspicious thoracic adenopathy was identified. Low FDG (fludeoxyglucose) activity and the very slow interval growth of the mass favored a benign or low-grade etiology such as well-differentiated carcinoid.
A right middle lobectomy was performed. Sectioning revealed a well-demarcated thinly encapsulated homogenous hemorrhagic nodule. There was no gross evidence of necrosis and/or fibrosis surrounding the nodule (Figure 2).
HISTOLOGIC AND IMMUNOHISTOCHEMICAL FINDINGS
Microscopically, the nodule was composed of an unencapsulated collection of dilated vascular spaces, variably filled with blood and separated by connective tissue stroma (Figures 3 and 4). A single layer of flat endothelial cells lining the vascular spaces was strongly positive for CD34 by immunohistochemistry. The lesion was therefore diagnosed to be vascular in origin.