Secondary spontaneous pneumothorax can be caused by a number of diseases, many of which are associated with the formation of subpleural cystic spaces which may rupture spontaneously. We describe a case of recurrant spontaneous pneumothorax caused by an extremely rare entity-cystic fibrohistiocytic tumor of the lung. To our knowledge only 4 such cases have previously been reported in the literature.
A previously healthy 35 year old African American woman was referred to the pulmonary clinic for evaluation of 2 episodes of spontaneous right sided pneumothorax. She had no previous history of lung disease and was a lifelong non-smoker. On both occasions which were 5 years apart she presented with sudden onset of unprovoked chest pain and dyspnea. She was not pregnant on either occasions and required chest tube placement for treatment of the pneumothoraces. Her past medical history was significant only for hypertension and depression. Her obstetric history was significant for uterine fibroids and tubal ligation. Her family history was unremarkable for lung disease or cancer. Physical examination revealed an obese lady with an otherwise normal exam. Chest x-rays between the two episodes revealed no obvious pleuro-parenchymal abnormalities. An HRCT of the chest( graphic 1) following resolution of the second episode revealed multiple thin walled cysts of varying size, many of which were pleural based.These were limited almost exclusively to the right upper and middle lobes with sparing of the right lower lobe and the left lung. A CT of the abdomen and pelvic ultrasound only revealed uterine fibroids. An autoimmune work up was negative. An exploratory thoracotomy revealed multiple pleural based cysts and a right upper and middle bilobectomy was performed. The lung biopsy showed numerous cystic spaces traversed by thick trabeculae which were lined by cuboidal cells and composed of bland fibrohistiocytic cells. Histologically these were most consistent with the diagnosis of cystic fibrohistiocytic tumor of the lung. Differential diagnoses of indolent proliferative processes presenting similarly with cyst formation were looked for with immunostaining and were all negative. These included HMB-45 (for Lymphangioleiomyomatosis), S-100 (for Langerhan’s histiocytosis), CD10( for low grade endometrial stromal sarcoma), HHF-35 (for metastatic low grade leiomyosarcomas)and fungal stains. The patient has been doing well with no evidence of disease recurrance for almost a year.
Cystic fibrohistiocytic tumor of the lung is an extremely rare proliferative process within the lung. Thus far only four cases have been described in the literature all in males. Its histogenesis is uncertain but the majority probably represent metastases from cellular fibrous histiocytomas, presenting as indolent skin lesions. However, rare cases may either be primary in origin or the primary site may be occult. The four cases reported thus far all had bilateral cavitating nodules or cystic lesions and presented with hemoptysis or pneumothorax. Three of them also had a history of previously excised fibrohistiocytic skin lesions. The spectrum of pulmonary fibrohistiocytic lesions ranges from benign fibrohistiocytoma, inflammatory pseudotumor fibrohistiocytic type, fibrohistiocytic lesions of borderline malignant appearance to unequivocal malignant fibrous histiocytoma. Apart from the rarity of the disease, the unilateral distribution of the lesions and the first report in a female patient make this case unique.
Primary cystic fibrohisitocytic tumor of the lung is an extremely rare but recognized cause of recurrant secondary spontaneous pneumothorax and should be considered in the differential diagnosis of unilateral or bilateral cystic lesions of the lung in young adults.
V. Pai, None.