To the Editor:—
In their interesting case report, "Thoracic Endometriosis With Recurrent Spontaneous Pneumothorax" (196:595, 1966), Drs. Kovarik and Toll note the apparent predilection of thoracic endometriosis for the right hemithorax. They point out that only one of the reported lesions was "in the left lung."I assume they refer to the patient reported by Dr. Jones and myself (New Eng J Med266:805, 1966) and would like to stress that the lesion was not in the pulmonary parenchyma but in the wall of a bronchus. The x-ray-film shadows seen in our patient disappeared between menses and doubtless represented blood.I fear this does not help in elucidating the mechanism for extragenital endometriosis, but keeping the difference in mind may help avoid confusion.