Pulmonary capillary hemangiomatosis: a lesson learned

Abstract

Pulmonary capillary hemangiomatosis (PCH) is a rare and controversial entity that is known to be a cause of pulmonary hypertension and is microscopically characterized by proliferation of dilated capillary-sized channels along and in the alveolar walls. Clinically, it is mostly seen in adults. Clinical features are characterized by nonspecific findings such as shortness of breath, cough, chest pain, and fatigue. It can be clinically indistinguishable from pre-capillary pulmonary arterial hypertension disorders such as primary pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension. However, the diagnostic distinction, which usually requires a multidisciplinary approach, is crucial in order to avoid inappropriate treatment with vasodilator medications usually used for PAH treatment. Prognosis of PCH remains poor with lung transplant being the only definitive treatment. We report an autopsy case of pulmonary capillary hemangiomatosis unmasked at autopsy that was treated with a prostacyclin analog, usually contraindicated in such patients. We emphasize that this entity should always be on the differential diagnosis in a patient with pulmonary hypertension and requires great vigilance on the part of the clinician, radiologist and pathologist to make the diagnosis and guide appropriate management.

Keywords: Pulmonary hypertension; Pulmonary veno-occlusive disease; pulmonary capillary hemangiomatosis; pulmonary heart disease.

Figure 1. Imaging findings associated with PCH, as seen on non-contrasted chest CT in soft tissue windows. A and B – axial views demonstrate evidence of significant pulmonary hypertension manifested by enlargement of the main pulmonary artery (thick white arrow) which measured 3.6 cm, as well as marked enlargement of the right atrium (thin white arrow) and right ventricle (white arrowhead); C (coronal view) and D (axial view) show the enlarged mediastinal and hilar lymph nodes, nonspecific, but which in the setting of pulmonary hypertension can be associated with PCH.

Figure 2. Imaging findings associated with PCH, as seen on non-contrasted chest CT in lung windows. A to F – sequential axial slices from the upper lung zones down to the lower lung zones demonstrate widespread geographic regions of pulmonary ground glass attenuation, which in the setting of pulmonary hypertension, raises the possibility of PCH. Although indistinguishable from PVOD on imaging alone, the relative paucity of septal thickening as compared to the degree of the ground-glass present may somewhat favor PCH over PVOD in the differential diagnostic consideration.

Figure 3. Gross findings of the lungs at autopsy (post-formalin fixation). A – Right; B – Left lung parenchyma revealing emphysematous changes and areas of consolidation with firm pulmonary parenchyma.

Figure 4. Photomicrographs of the lung. A – thickened alveolar walls with increased capillary density and passive congestion; B – increased capillary density and congestion in the alveolar walls with hemosiderin-laden macrophages in the alveolar spaces; C – Muscularized arteriole within the alveolar septa with intimal thickening and medial hypertrophy characteristic of pulmonary hypertension (H&E, A 40X, B 100X, C 100X).

Figure 5. Photomicrographs of the lung. A – Iron staining highlights hemosiderin in alveolar walls and in the alveolar spaces (Perls Prussian blue stain, 100X); B – reticulin stain revealing the increased number of capillary walls in alveolar walls (Verhoeff van Gieson stain, 100X); C – CD31 stain revealing increase vessel proliferation in alveolar walls (100X).