Pleural inflammatory myofibroblastoma: a locally aggressive intra-thoracic tumour
© Kubal et al; licensee BioMed Central Ltd. 2007
Received: 16 January 2007
Accepted: 28 June 2007
Published: 28 June 2007
A 41-year old non-smoking woman presented with persistent pleural effusion. Pleural fluid was hemorrhagic and fluid cytology was negative for malignant cells. A working diagnosis of chronic haemothorax was made and standard right thoracotomy was performed to identify the source of bleeding. A 10 × 10 cms poorly circumscribed mass containing blood clots, altered blood, fibrous tissue, and gelatinous debris was found and demonstrated features of inflammatory myofibroblastoma on immunohistochemistry. Thirteen months later, the patient developed a local recurrence, which was treated surgically. Semi-solid physical appearance of this tumour has not been reported previously. This case report further adds to the diagnostic dilemma related with this tumour.
Inflammatory myofibroblastic tumour is a rare entity. These tumours are well known for their bizarre presentation and behaviour. This case report further supports their variability in presentation. We present a case of pleural inflammatory myofibroblastoma that presented as a chronic haemothorax.
However, 13 months later, the patient presented again with an increasing right-sided pleural effusion. A CT scan revealed a soft tissue mass in right costophrenic recess. This was thought to be due to recurrence of the initial tumour and right thoracotomy was performed. A poorly circumscribed gelatinous tumour measuring 5 × 7 cms was present in the right costophrenic angle involving adjacent diaphragm, pericardium and visceral pleura of the right lower lobe. A right lower lobectomy was performed along with resection of right hemi diaphragm and involved pericardium. The defects were repaired with a patch. One year later, the patient was asymptomatic and CT-scan revealed no tumour recurrence.
Inflammatory myofibroblastoma can occur in many parts of the body. Its histological elements are myofibroblasts, histiocytes, plasma cells, and lymphocytes. Presence of these features suggests that this is a fibro-inflammatory lesion with abnormal extension of the reparative healing process after an unknown insult. Inflammatory myofibroblastoma is rarely found in the pleural space. It is also uncommon amongst tumours of the lung with an incidence varying from 0.04%  to 0.7% , but is rare in the pleural space. It has also been reported to arise from diaphragm , heart, and many extra-thoracic locations such as liver, spleen, testes, epididymis, spermatic cord, bladder, salivary glands, spinal meninges and orbit.
The characteristics of this tumour include its bizarre presentation and unknown natural history, as in the case presented. This tumour may have variable physical consistency. Apart from semi-solid gelatinous consistency presented in this case it can also present as a solitary nodule  and solitary or multiple calcified fibrous nodules . It can easily be confused with lung cancer when it appears as a solitary nodule on CT scan. Both benign and malignant pleural conditions can be confused with the non-solid presentation of this tumour. The case of inflammatory myofibroblastoma presented in this case report is unique due to its presentation as a long-standing haemothorax and it's non-solid physical appearance. This only adds to the diagnostic dilemma related with this tumour. Surgical treatment can be challenging in non-solid tumours, as complete removal can be difficult; resulting in a high risk of local recurrence. Distant recurrence has been reported as early as 3 months in the form of multiple bilateral pulmonary nodules and occurrence in multiple organs after lung resection has been reported . On the other hand two different series consisting of seven patients each have reported no evidence of recurrence with follow-up ranging from 0.5–13 yrs [7, 8].
This case report emphasizes the difficulty in making preoperative diagnosis of pleural inflammatory myofibroblastoma. This lesion should be kept in mind when dealing with non-resolving haemorrhagic pleural effusions in absence of a suspicious malignant lesion. A low threshold to perform CT guided biopsy may offer preoperative diagnosis and better planning of surgical management in these tumours.
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