Figure 1.

Histological findings in FIGF mutation. A: Pulmonary arteries showed tortuosity and ectasia, imparting a baggy appearance (hematoxylin and eosin stain). B: Their irregular contours were highlighted by elastic tissue staining. C: Low magnification showed ectatic pulmonary veins as well as unremarkable alveolar architecture. D: Frequent airway neuroendocrine cells (highlighted brown by a synaptophysin stain) were present, occurring singly and within clusters. E: In a control patient with normal lung vasculature (pneumonectomy specimen from a 2-year-old boy with an untreated benign lung tumor), the pulmonary arteries are smaller than the corresponding bronchus; they lack tortuosity and do not undulate in and out of the plane of section. Original magnification: ×200 (A, B, and D); ×20 (C); ×100 (E).