Primary pulmonary hypertension (PPH) has been aptly defined by Evans 1 as hypertension of the lesser circulation in the absence of heart disease (other than cor pulmonale), parenchymal lung disease, or vascular disease of known etiology involving the pulmonary arterial tree. The histologic appearance of the lungs in recorded cases of primary pulmonary hypertension suggests that this designation includes more than one disease entity.
We have had the opportunity to study, clinically and at autopsy, four examples of PPH. On the basis of the histologic appearance of the lungs these cases appeared to form a well-defined group, suggestive of a single disease entity. Clinically and pathologically there was also noted an unusually high incidence of certain features which apparently were not the result of pulmonary hypertension. These were Raynaud's phenomena, arthritis, certain lesions suggestive of "collagen" disease, and similar symptoms in close relatives (Table 1).
The above findings prompted