Immunocytochemical detection of progesterone receptors. A study in a patient with primary pulmonary hypertension.

Primary pulmonary plexogenic arteriopathy (PPPA) is one of the principal conditions in which pulmonary hypertension may be clinically unexpected. It occurs in the lung vessels in the absence of any demonstrable cause. Its high incidence in women of childbearing age combined with reports of disease following delivery of a child or assumption of oral contraceptives suggest that hormonal factors may play a role in the pathogenesis of PPPA. The suspicion that the pulmonary vascular lesions occurring in PPPA could represent the effect of a hormonal mediated vascular hyperreactivity prompted the evaluation of the steroid hormone receptor status on lung tissue obtained from a women suffering from this disease who had a double-lung transplantation. By the immunocytochemical method performed on formalin fixed, paraffin-embedded lung tissue, we showed the presence of progesterone receptors (PR) in the nuclei of the myofibroblasts forming the arterial obstructive intimal proliferations and of the spindle cells present in the walls of the plexiform lesions. To enhance the staining and to facilitate the observation, we used a microwave-based antigen unmasking technique. The lack of estrogen receptors and the presence of PR could have increased, in the case, the sensitivity of the pulmonary muscular arteries to vasoconstrictory compounds. We hypothesize that on this substrate of a presumptive steroid-mediated vasoconstriction the sequence of the histologic lesions characteristic of pulmonary vascular hypertensive disease could have developed.