Pulmonary Pathology

Authors

Samuel Guzman, MD (Fellow), Daniel Luthringer, MD (Faculty)

Subject: Pulmonary Pathology
Clinical History

A 67-year-old female with a history of pulmonary hypertension, right heart failure and COPD that presented for dyspnea, dizziness and near syncope episodes. The patient had symptoms of dyspnea on exertion for many years prior and had been on 4 L oxygen by nasal cannula. She was referred for a cardiac consultation when it was revealed that she had proven pulmonary hypertension by echocardiogram and right heart catheterization. A chest CT performed at that time demonstrated emphysema at the apices of her lungs and areas of dense ground glass opacifications without definite honeycombing seen on imaging so interstitial lung disease could not be diagnosed. A pulmonary function test revealed results that were consistent with pulmonary emphysema, pulmonary vasculitis disease or interstitial lung disease. Her evaluations concluded that she had pulmonary hypertension that was likely secondary to a lung disease of unclear etiology. She began treatment for pulmonary hypertension as well as being started on high dose steroids.

She again presented due to exacerbations of her heart failure and for worsening respiratory distress. She had her oxygen increased in order to keep her from decompensating. Increased doses of her medication offered little help. Her laboratory values continued to increase with a BMP of 3580 and worsening kidney failure. A chest X-ray revealed an enlarging cardiac silhouette with increased pulmonary vascular congestion relative to earlier imaging. On her last visit, she was requiring 15 L of oxygen with BIPAP in order to maintain her oxygen saturation. Her CT Chest at this time also showed evidence of worsening disease. After much discussion, the decision was made to taper off her steroids and discontinue other medications. She was started on comfort care treatment and made DNAR and expired soon afterward. An autopsy was performed.

Lung parenchyma, emphysematous, pathology, Cedars-Sinai

Figure 1: Lung parenchyma revealing emphysematous changes (black arrow) and areas of consolidation (blue arrow).

H and E, thickened alveolar walls, congestion, Pathology, Cedars-Sinai

Figure 2: H&E reveals thickened alveolar walls with increased microvessel density and congestion.

congestion, alveolar walls, hemosiderin laden macrophages, alveolar spaces, pathology, Cedars-Sinai

Figure 3. H&E revealing increased microvessel density and congestion in the alveolar walls with hemosiderin laden macrophages in alveolar spaces.

Iron stain, highlights, hemosiderin, alveolar walls, alveolar spaces, Cedars-Sinai, Pathology

Figure 4: Iron stain highlights hemosiderin in alveolar walls and in the alveolar spaces.

Figure 5: Reticulin stain revealing the increased number of capillary walls in alveolar walls.

Figure 6: CD31 stain revealing increased vessel proliferation in alveolar walls.

Discussion

Pulmonary capillary hemangiomatosis is a rare cause of pulmonary hypertension that is typically seen in younger adults but can occur in an age range from 2-72. It has an unknown etiology with an unfavorable prognosis of death within 3-5 years from the time of diagnosis. Patients typically present with progressive dyspnea as their major complaint but can also have hemoptysis, chest pain, cough and fatigue. Their pulmonary function tests usually include a normal forced vital capacity and normal expiratory volume with a markedly increase diffusion capacity. Right heart catheterization will usually have markedly elevated pressures which are indicative of pulmonary hypertension. Radiologically these patients typically have changes that are also consistent with pulmonary hypertension with features that include: bilateral interstitial infiltrates, cardiomegaly, and enlargement of the pulmonary arteries.

On gross exam the lungs will typically appear congested and have an edematous appearance without significant fibrosis. The characteristic pathological finding that is seen microscopically is a proliferation of thin-walled microvessels infiltrating the peribronchial and perivascular interstitium of the lung parenchyma and pleura. These vessels are prone to bleeding which results in hemorrhage and hemosiderin-laden macrophages in the alveolar spaces. In order to make the diagnosis there must be at least 2 layers of aberrant capillaries that are seen within the alveolar wall. The proliferation of the microvessels extends into the larger vessels (arterioles and venules) which results in luminal narrowing or obliteration. It is the involvement of the larger vessels that results in pulmonary hypertension. The typical characteristics of pulmonary hypertension will also be seen which include intimal thickening and medial hypertrophy of the small muscular arterials but in contrast to other forms of pulmonary hypertension the presence of plexiform lesions will not be observed. Special stains and immunohistochemistry are not necessary to diagnose pulmonary capillary hemangiomatosis but they can help visualize the features. Endothelial markers such as CD31 or CD34 will highlight the proliferation of capillary endothelial cells. Trichrome or a Movat Pentachrome stain can also be used to highlight the supporting collagen of the loop lesion and occluded veins that are seen in other causes of pulmonary hypertension such as Pulmonary Veno-Occlusive Disease but not in PCH.

References

1. Almagro P, Julia J, et al. Pulmonary Capillary Hemangiomatosis Associated with Primary Pulmonary Hypertension: Report of 2 New Cases and Review of 35 Cases from the Literature. Lippincott Williams & Wilkins. Medicine. 81, p417-424, 2002

2. O'Keefe M, Post M. Pulmonary Capillary Hemangiomatosis: A Rare Cause of Pulmonary Hypertension. Archives Pathology Lab Med. Vol 139, Februaru 2015

3. Wick L, et al. Pulmonary Hypertension. Practical Pulmonary Pathology: A Diagnostic Approach. Elsevier Saunders, 2nd edition 2011: Ch 11: p375-390

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