Pulmonary venoocclusive disease/pulmonary capillary hemangiomatosis: Inadequacy of clinico-radiologic features in diagnosis.

Pulmonary venoocclusive disease (PVOD)/pulmonary capillary hemangiomatosis (PCH) belongs to the WHO group 1 pulmonary hypertension (PH), labeled as pulmonary arterial hypertension (PAH), though it mainly involves pulmonary veins, venules and capillaries. PVOD/PCH may occur as a pure form, with other types of PH, or with fibrotic interstitial lung diseases (ILDs). Recognition of PVOD/PCH is crucial as vasodilators used in PAH patients may cause severe pulmonary edema in PVOD/PCH patients. Since biopsy is relatively contraindicated in PAH given the high risk of complication, high resolution computed tomography (HRCT) plays an important role in the diagnosis of PVOD. Centrilobular ground-glass opacities (cGGO), interlobular septal thickening (IST) and mediastinal lymphadenopathy (mLAD) have been described as the triad of HRCT findings for PVOD/PCH but the sensitivity and specificity of this triad in different settings of PVOD/PCH have not been well characterized. In the present study, we compared the clinical and HRCT findings in different settings of PVOD/PCH. Cases of PVOD/PCH diagnosed with surgical lung biopsy, explant or autopsy were identified from the pathology archives (2003-2026) and categorized into 3 groups: pure PVOD/PCH (group 1, n = 14), PVOD/PCH with other types of PH (group 2, n = 3), and PVOD/PCH with fibrotic ILD (group 3, n = 6) after re-review of all slides to confirm the diagnosis. Clinical and radiologic findings were systematically evaluated and compared across these 3 groups. Mean ages at diagnosis were 51, 39, and 58 years in groups 1, 2, and 3, respectively. Median values for mean pulmonary arterial pressure were 51.0, 55.0, and 49.0 mmHg in groups 1, 2, and 3, respectively. There was no significant difference in sex or smoking status across the 3 groups. HRCT showed following results in groups 1, 2 and 3: cGGO in 57.1%, 66.7%, and 0% (p = 0.03); IST in 64.3%, 66.7% and 16.7%; mLAD in 85.7%, 66.7%, 83.3%. At least two of the three features of the triad of cGGO, IST, and mediastinal LAD were present in 10 of 14 (71.4%), 2 of 3 (66.7%), and 1 of 6 (16.7%) of group 1, 2 and 3 cases respectively. There was insufficient statistical power to detect potential trends in clinical and radiographic patterns across subgroups (with exception for cGGO), due to the small number of cases. Taken together, some PVOD/PCH cases in all groups of our cohort lacked the triad of HRCT findings and most patients were unsuspected of PVOD/PCH based on clinico-radiologic features. In conclusion, the role of pathologists would be highly important to raise the awareness of potential PVOD/PCH to pulmonologists given the therapeutic implications.