{"paper_id":"5fc3160e-5929-49fb-88f9-667b7d632d31","body_text":"Intrathoracic endometriosis is classified into pleurodiaphragmatic endometriosis and\nbronchopulmonary endometriosis according to the migration of endometrial tissue.\nBronchopulmonary endometriosis is rare. Intrathoracic endometriosis frequently\noccurs in the right thorax ( 1 ). Computed tomography (CT) findings of bronchopulmonary endometriosis\nare lung nodules, with or without cavities, or surrounding ground-glass opacities\n(GGO). Features vary with menstrual status ( 2 , 3 ).\nRecently, the usefulness of magnetic resonance imaging (MRI) was reported for the\ndiagnosis of intrathoracic endometriosis, but most published reports were about\npleurodiaphragmatic endometriosis ( 4 – 9 ). We present CT and MRI findings of\nbronchopulmonary endometriosis that showed a gradually enlarging nodule in the left\nlung.\n\nA 49-year-old woman received a routine medical check-up. An abnormal shadow was found\non chest X-ray (CXR). She visited her home doctor and underwent a CT scan. CT showed\na nodular lesion in the left lower lobe and she was referred to our hospital.\nHer medical interview revealed that she suffered flu-like symptoms and hemoptysis two\nmonths previously and was cured by medication within one week. The relation between\nthe symptoms and menstrual period was not clear.\nHer past surgical history was an operation for descensus uteri 16 years previously\nand her obstetric history was two deliveries and two abortions. Her smoking history\nwas 20 pack-years and she was an ex-smoker and who had quit smoking about one year\npreviously. Complete blood count and blood chemistry were normal. No coagulation\ndisorder was found.\nCXR revealed a nodular shadow in the left lower lung field ( Fig. 1a and b ). CT showed a round-shaped\nnodule with a smooth border in the left lower lobe adjacent to the pleura. The long\naxis of the nodule was 20 mm on CT ( Fig. 2a ). The differential diagnosis was pulmonary hamartoma, sclerosing\npneumocytoma, and solitary fibrous tumor of the pleura. She was followed up by her\nhome doctor.\n(a, b) CXR showed a nodular shadow in the left lower lung field (white arrow)\non first visiting to our hospital.\nPre- and post-contrast-enhanced CT. (a) CT showed a round-shaped nodule in\nthe left lower lobe on the first visit to our hospital. The nodule was\nenlarged ten months later and contained (b) small high-density areas with\n(c) inhomogeneous enhancement and there was no GGO or consolidation\nsurrounding the nodule (d).\nTen months later, hemoptysis recurred and she visited our hospital again. CT revealed\nthat the nodule enlarged to 30 mm in the long axis. The nodule consisted of a\nlow-density area and a small high-density area and showed inhomogeneous enhancement.\nThere was no GGO or consolidation surrounding lung parenchyma ( Fig. 2b–d ). T1-weighted (T1W) imaging and\nT2-weighted (T2W) imaging both showed high and low signal intensities in the nodule;\nit was partly enhanced after injection of contrast medium ( Fig. 3 ). A signal void in the nodule may have\nreflected cavity formation or hemosiderin deposition. Diffusion-weighted imaging\n(DWI) showed a diffusion-restricted area and an enhanced area in the nodule ( Fig. 4 ). The nodule had\nincreased in size and malignancy was suspected. Video-assisted thoracotomy was\nperformed. In thoracoscopic findings, there was no pleural lesion and the nodule was\nlocated in the subpleural lung parenchyma. She had a good course and without any\ncomplications after surgery.\nT1W imaging, T2W imaging, and contrast-enhanced T1W imaging. T1W (a) and T2W\nimaging (b) both showed high and low signal intensity areas and a small\nsignal void in the nodule. (c) After administration of contrast medium,\nthere was a nodular enhancing area in T1W imaging\n(a, b) DWI and apparent diffusion coefficient (ADC) map. In DWI (b = 1000),\nthe nodule had a diffusion-restricted area (black arrow head) and an\nenhanced area (white arrow).\nFormalin-fixed material showed a yellowish-white colored nodule protruding from the\nlung parenchyma. Hemorrhage was visible in the central area in the nodule.\nMicroscopically, endometrial tissue with many glands and interstitia were found.\nThere was hemorrhage with tissue laceration and hemosiderin deposition in only a\nsmall part. In adjacent lung parenchyma, collagen was deposited in a band-like area\ncontaining bronchiolar or other lung tissue. A large number of hemosiderin-laden\nmacrophages were observed in the surrounding lung parenchyma caused by pulmonary\nhemorrhage ( Fig. 5 ). The\nfinal pathological diagnosis was bronchopulmonary endometriosis.\nMicroscopic findings (hematoxylin and eosin stain 20). Microscopic view\nrevealed endometrial tissue with hemorrhage and hemosiderin-laden\nmacrophages surrounding the alveolar space Microscopic view revealed\nendometrial tissue with hemorrhage and hemosiderin-laden macrophages\nsurrounding the alveolar space.\nAfter surgery, her symptoms disappeared and no recurrence was seen even without\nhormonal therapy for about five years.\n\nIntrathoracic endometriosis is classified into two categories, pleurodiaphragmatic\nand bronchopulmonary endometriosis. This case was categorized as the latter and\nendometrial tissue was in the bronchiole or lung parenchyma. Pregnancy, delivery,\nand hysterectomy are risk factors. The right thorax is predominant and hemoptysis or\nhemosputum within the menstrual period are general symptoms ( 1 ). However, in other reports there was no\nlaterality in bronchopulmonary endometriosis compared with pleuro-diaphragmatic\nendometriosis ( 2 ). Several\netiologies were hypothesized and microembolism of endometrial tissue is the most\nlikely one. Risk factors are trauma or uterine manipulation. According to this\nhypothesis bronchopulmonary endometriosis would occur in both lungs. However,\ncatamenial hemoptysis is also a symptom of bronchopulmonary endometriosis, and this\nsymptom shows right-side predominance ( 1 ). Clearly explaining the reason for\nlaterality of bronchopulmonary endometriosis has not been possible and further\ndiscussion is needed.\nBronchopulmonary endometriosis usually results in a hematoma or alveolar hemorrhage\nin the lung. Consolidation, nodular shadow, or miliary shadow were reported on CXR.\nCT showed consolidation, GGO, nodules with cavitation, or GGO surrounding lung\nparenchyma. The lesions appeared or disappeared in relation to menstruation, so a\nnormal image finding was also possible ( 2 , 3 ).\nIn this case, the nodule gradually enlarged and we suspected a malignant tumor.\nBronchopulmonary endometriosis occurs during the child-bearing years and showed\nvarious CT findings; nodules appeared in more elderly women compared with other\nentities of thoracic endometrial syndrome. Joseph et al. supposed hormonal weakness\nis not involved in aggressive findings such as cavity formation or surrounding\nhemorrhage ( 1 ). This case\nwas a 49-year-old premenopausal woman. The pathological findings showed a soft\norganization lacking constrictive fibrosis and with no marked menstrual hemorrhage\nor tissue response.\nRecently, the usefulness of MRI for the diagnosis of thoracic endometriosis was\nreported ( 4 – 9 ). T1W imaging showed high signal intensity\nand DWI was sensitive for small hematomas in pleurodiaphragmatic endometriosis\n( 5 , 7 , 9 ). To the best of our knowledge, there has\nbeen no report about MRI findings of bronchopulmonary endometriosis. In this case,\nT1W and T2W imaging both showed high and low signal intensity and DWI showed\ndiffusion-restriction and enhancement areas in the nodule, probably caused by\nhematoma during various periods. Low signal intensity in the part of the nodule\nshowed that contrast enhancement might correspond to endometrial tissue. Therefore,\nthese MRI findings are valuable for diagnosis. A signal void in the nodule may\nreflect cavity formation or hemosiderin deposition. Pathological findings revealed\nthere was collection of red blood cell in dilated endometrial glands and a small\namount of hemosiderin or hemosiderin-laden macrophages were present in the\ninterstitium of the endometrial tissue. The nodule was composed of fresh hematoma\nand hemosiderin deposition, so these findings might reflect various periods of\nhemorrhage in MRI.\nPleurodiaphragmatic endometriosis and bronchopulmonary endometriosis also showed\nhemorrhagic disease and showed similar signal intensities in MRI. The difference\nbetween these two diseases can be seen where there is endometrial tissue in pleura\nand the diaphragm or lung parenchyma. Bronchopulmonary endometriosis showed cavity\nformation or GGO and consolidation in the form of pulmonary hemorrhage in CT.\nHowever, catamenial hemoptysis is more important for diagnosis. MRI findings of this\ncase showed a hemorrhagic nodule with a partly enhanced area. These findings are not\nspecific in bronchopulmonary endometriosis and also show hematoma with granulation\ntissue in pulmonary laceration, hemorrhagic nodules such as metastatic\nchoriocarcinoma, or angiosarcoma. If catamenial hemopysis is present, a diagnosis of\nbronchopulmonary endometriosis is possible and past clinical histories are also\nhelpful for diagnosis.\nWe reported a case of bronchopulmonary endometriosis that occurred in the left lung.\nThe disease showed a gradually growing pulmonary nodule with an enhanced area. T1W\nimaging, T2W imaging, and DWI showed signal intensity of hemorrhage during various\nperiods and enhancing areas associated with endometrial tissue.","source_license":"CC0","license_restricted":false}