Extensive Right Pleural and Chest Wall Malignant Fibrous Histiocytoma at an Unusual Age: Computed Tomography Features

Aims: To describe a rare case of malignant fibrous histiocytoma at an unusual age of sixteen (16) years. Also to sensitize the medical community to the need for thorough evaluation of an opaque hemithorax and to describe the imaging features of this rare neoplastic disease. Presentation of Case: This was a 16 year old girl who presented with progressive swelling and recurrent right chest pain of 10 months duration and difficult breathing of 6 weeks duration. There was associated weight loss, dry cough and low grade intermittent fever. She had solitary cervical lymphadenopathy, grade II finger clubbing and low hematocrit. Discussion: Malignant fibrous histiocytomas (MFHs) are tumors of adulthood with a mean age of 59 years. It has predilection for the extremities, the abdominal cavity and the retroperitoneum. Primary pleural occurrence is relatively rare. This is a rare case of an extensive malignant fibrous Case Study histiocytoma of the right pleura with chest wall involvement presenting at an unusual young age of 16 years, at variance with the ages documented in the literatures. Imaging findings of the histologically proven tumor were also described on high resolution chest Computed Tomography. Conclusion: Malignant fibrous histiocytomas may occur much earlier than the age documented in most literatures. This case showed that not all cases of extensive opaque hemithorax are due to massive pleural effusion and further and better diagnostic imaging will be necessary for prompt and proper management.


INTRODUCTION
Most pleura or chest wall tumors are often secondaries from cancers of the breast, lung, kidney, thyroid and multiple myeloma of the ribs [1,2]. Primary MFHs of the pleura are now called pleomorphic undifferentiated sarcomas by the World Health Organization (WHO) tumor classification [3]. Pleura MFHs are relatively rare tumors, despite the fact that MFHs are the most common soft tissue sarcomas in adults [4], accounting for about 20-30% of all soft tissue sarcomas. MFHs are known to have predilection for the extremities, abdominal cavity, and retroperitoneum [2], they occur in adults with age range of 32-80 years [5]. This is a case report of an extensive MFH of the right pleura (hemithorax) occurring at a rather young and unusual age of 16 years with late presentation. Also described are the Computed Tomographic features. A 16 year old girl who presented with progressive swelling and recurrent right chest pain of 10 months duration and difficulty in breathing of 6 weeks duration. There was associated weight loss, dry cough and low grade intermittent fever. However, there was no associated hemoptysis. Clinical examination revealed a well oriented, chronically ill-looking young girl. Essentially, she had grade 2 finger clubbing and a 0.5 x 0.5 cm solitary right cervical lymph node. No enlarged lymph nodes were found elsewhere. The Vital signs, with the exception of the respiratory rate, were within normal limits; Pulse rate was 74/min, Blood Pressure was 90/60 mmHg.

Systemic Examination
Essential systemic findings were in the chest and abdomen. Chest examination revealed a respiratory rate of 26/min, outward bulging of the right hemithorax, tracheal deviation to the left, and dull percussion note also in the right hemithorax with markedly reduced breath sounds. Abdominal examination showed tender hepatomegaly and the liver was down by 9 cm below the costal margin in the right mid clavicular line.

Laboratory and Imaging Findings
Laboratory results showed reduced haematocrit of 25%, other laboratory parameters were within normal range. She had a chest tube inserted due to the initial chest X-ray finding of an opaque right hemithorax from suspected massive pleural effusion and possible intra thoracic mass at the referring hospital. This was said to have drained some hemorrhagic fluid containing some tissues. Chest X-ray taken at the referring hospital was however not provided.

Histopathology
The patient had percutaneous transthoracic needle biopsy at our hospital and histopathological findings revealed mesenchymal neoplasm composed of proliferating spindle to polygonal cells, some with wavy spindle nuclei exhibiting moderate pleomorphic. These cells were supported by loose myxoid stroma. Skeletal muscle bundles were invaded and destroyed by the tumor cells. Mitotic figures were present but no definite area of necrosis was noted (Figs. 1A and 1B).
Overall features were those of malignant solitary fibrous tumor. Surgery was not contemplated, due to the extensive nature of the disease, the distant cervical node secondary and the late presentation.

Treatment
She however had chemotherapy with eight courses of Vincristine, Actinimoycin, Cyclophosphamide and prednisolone combination (VAC-P) and palliative radiotherapy. There was slight improvement in patient's condition over time. Patient however died of cardiorespiratory arrest after six and a half month on palliative treatment.

Computed Tomography Imaging Findings
High resolution pre and post contrast Computed Tomography scan of the chest was acquired with a 64 slice Multidetector Toshiba Aquilon CT scanner. The plane chest image (scanogram) show complete opacification of the right hemith-orax with abnormal lateral bulging of the anterolateral chest wall (Fig. 2).

Fig. 2. Plain chest image (CT scanogram) shows almost complete opacification of the right hemithorax, widened intercostal space, medistinal shift to the left and inferior displacement of Right hemidiaphgram and liver inferiorly
Axial (Figs. 3A and 3B) and multiplanar reconstructed Computed Tomography images confirmed complete opacification of the right hemithorax with abnormal lateral bulging of the anterolateral chest wall.
There is an extensive solid heterogeneous mass occupying almost the entire right hemithorax. The mass showed isodense to slightly hypodense mass to the muscle with heavy as well as amorphous calcification, majorly in the periphery of the mass (Fig. 4).
Irregular air pockets were seen within the mass presumably due the chest tube inserted during the course of treatment at the referring hospital and also in the upper thoracic cavity. There was associated expansion of the hemithorax with some extension to the anterolateral chest wall. In addition, there was atelectasis of the right lower lobe and middle lobe, with displacement of the mediastinum to the left and some extension of the right hemithorax massacross the midline to the left were noted. The aforementioned mass also showed inferior extension with displacement of the ipsilateral hemidiaphgram, the liver and the kidney inferiorly. Associated widening of the intercostal spaces with destruction of the 6 th to 8 th rib lateral aspect were also noted (Fig. 5).

DISCUSSION
MFHs are deep seated pleomorphic sarcomas of controversial origin that usually presents in middle aged adults [2,6]. Although Jin-Kyung et al. [6] reported a case of MFH in a 25 year old, a younger age compared with the ages in the existing literature, this case report appears to be the first to be discovered at the age of 16 years.
MFH was first described by O'Brien and Stout in 1964 as tumors of histiocytic origin [7]. These tumours were documented to be composed of varying amount of fibroblast like and histiocytic like cells in varying proportion [8]. Although, some authors believed this tumor is the end of the spectrum of soft tissue tumors as they become undifferentiated. [2,8,9]. MFHs were however, recognized as an entity and named undifferentiated pleomorphic sarcoma (UPS) in 2002 by the World Health Organization [3]. Using the WHO nomenclature, Guo et al. [8] noted that MFH/UPS always express Vimentin and that some of these tumors showed positivity for myogenic antigen and CD68. MFHs have been classified into subtypes according to their aggressiveness and the cell type [10]. Documented subtypes of MFH in the literature includes the storiform/pleomorphic type, the most frequent histological type accounting for about 50% to 60% of all MFHs. The myxoid type is the second most common but the least aggressive of the MFHs. Others are the giant cell and the inflammatory types [10].
MFH commonly arise from the deep fascia and the skeletal muscles [6,10] of the extremities and the retroperitoneum [6,10,11]. MFHs of the lower extremities account for 59% of all reported cases. Other sites of affectation reported in the literatures are the lung, the liver, the kidney, the bladder, the scrotum and the vas deferens. MFH of the heart, aorta, stomach, small intestine, orbit, the central nervous system, para spinal region, dura matter, facial sinuses, nasal cavity,

3A 3B
oral cavity, nasopharynx, and soft tissues of the neck have all been documented [11]. The pleura and chest wall as reported in this case, is however an unusual and rare site. MFH may develop as a primary tumor or secondary to old pleurisy, pyothorax, radiotherapy and post thoracotomy [12]. This case report appears to be of the primary type as there were no previous clinical history to suggest a secondary MFH in this patient.

Fig. 5. Volume rendered image shows the extensive right hemithorax mass and overlying 6th-8 th rib anterolateral destruction
Clinically, these tumors presents with painless mass that is slow growing in nature over weeks to months. Advanced disease may present with fatigue and weight loss, while large retroperitoneal tumors could present with anorexia and increased abdominal pressure [8], fever and malaise [13]. Other rare clinical presentations were cases of gluteal abscess, episodic hypoglycemia and rapidly enlarging tumour in pregnancy [14].
Associations with non-Hodgkin's and Hodgkin's lymphoma, multiple myeloma and malignant histiocytosis have been documented [12,15]. In this case the patient had slowly enlarging right hemithorax from the progressive tumor growth. There was associated weight loss and intermittent low grade fever. All consistent with the documented features in the literatures [8,13].
The associated chest pain in this case was probably due to pressure effect of the mass on contiguous structures. The grade 2 finger clubbing, though not commonly documented in literatures, could be due to marked reduction in blood oxygen from the extensive lung collapse from the right hemithorax MFH.

Role of Imaging
Radiological imaging is crucial for detailed description of the tumor including the extent and involvement of adjacent tissues as well as distant metastases, which will be invaluable in surgical planning. Imaging is also essential in the differential diagnosis, follow up and prognostication. Imaging techniques employed in the evaluation of MFH includes plain X-ray, Ultrasonography, Computed Tomography, Magnetic resonance imaging, Nuclear imaging Angiography and Positron emission tomography (PET). Plain films though non-specific may show local soft tissue mass with or without calcifications. Adjacent bone erosion or destruction, a feature that distinguishes it from soft tissue sarcomas except in synovial sarcomas, may be a pointer to the diagnosis [15]. Ultrasonography (USS) has the advantage of being cheap, readily available and ionizing radiation free. USS may show a heterogeneous well-defined, lobulated solid intrathoracic mass which may be isoechoic to muscle with hypoechoic areas of necrosis or hemorrhage and calcific high reflective areas. Computed Tomography is very useful in the description of the MFH soft tissue density mass, usually similar to muscle attenuation, with areas of nodular or peripheral enhancement post contras [15] as well as central hypodense areas due to hemorrhage, necrosis or myxoid area. Osseous involvements like bony erosion, bone destruction or fracture are well visualized on CT. CT show no fat density in MFH, a distinguishing feature from liposarcomas. In this case, CT features were consistent with those documented in the literatures [15]. No fat density was seen on CT images, thereby excluding liposarcomas as a possible differential.
MRI is an excellent imaging modality, particularly for peripheral soft tissue tumors [15]. It is ionizing radiation free unlike most other modalities and has excellent soft tissue contrast in multiple planes. MRI will show the extent of the soft tissue mass by clearly differentiating the tumor from the muscles [15]. MFH is usually heterogeneous in intensity on all sequences due to different components or from hemorrhage, fibrous tissue and calcifications.
Although MFH signal intensities are non-specific, Myxoid MFH may show low signal intensity on T1-weighted images and prominent high signal intensity on T2-weighted images due to the high water content of these lesions [7,15]. Calcific foci and sub-acute hemorrhage may be seen as low and high signal on both T1-weighted and T2weighted sequences respectively. While necrotic areas may show a fluid signal pattern. Post Gadolinium scans, typically reveal nodular and peripheral enhancement of MFH solid components. And a relatively well defined tumor margin of low signal intensity presenting the tumor pseudo capsule may be observed [15]. Angiography is nonspecific, but MFH usually shows a hypervascular mass with early venous return [16] while some MFH show hypovascular angiograms [17]. Sen et al. [4] reported the use of Positron emission tomography/computed tomography in defining primary MFH and secondaries. There was an enlarged cervical node, indicating secondary deposit in this case. Definitive diagnosis is however made by histology.
Appropriate MRI, PET and Angiography were not available and were not done in this patient.

Treatment
Management is usually multidisciplinary. Surgical resection of the primary mass is the mainstay of treatment [2,6]. Adjuvant treatment with Radiotherapy and Chemotherapy are usually instituted to prevent local recurrence or secondaries to other organs particularly in patients with high probability of recurrence especially in patients with retroperitoneum and head and neck sarcomas.
Although, chemotherapy results have not been shown to be effective and in general, adjuvant therapy has not been proven to improve survival in MFH [18]. Recent studies however, has indicated that Doxorubicin and Ifosfamide are the most active drugs against MFH with documented response rate of 10% and 36% [19]. This patient however had Vincristine, Actinimoycin, Cyclophosphamide and prednisolone combination (VAC-P) possibly due to the initial working diagnosis of intrathoracic tumour before the histopathology result and subjective assessment of some improvement.
MFH prognosis depends on the tumor grade, depth, size, metastatic status, patient's age, and histologic subtype. However, certain features like the tumour location (MFH of the abdominal cavity, the retroperitoneum or the head and neck), a tumor size of 5 cm or more, deep tumor location and high grade tumor generally have poor prognosis [20]. It is worthy of note that most MFH are of the high grade histologic type [21] and usually present with distant metastasis at the time of diagnosis [12]. Literature have also documented that most cases do recur locally despite the institution of aggressive treatment while the overall 5 year survival is documented to be between 25-70% [21].
In this case, the extensive nature of this tumor, bony destruction, compressive features, and the cervical node secondary as well as the relatively young patient's age were pointers to the poor prognosis. And surgery was not contemplated in this case due to the poor prognostic factors.

CONCLUSION
This is a case of an extensive malignant fibrous histiocytoma of the pleural and the chest wall occurring at an unusual young age and presenting late to the tertiary health facility. Treatment with radiotherapy and chemotherapy yields no or very little result. This case report emphasize the need for further evaluation and the use of better diagnostic imaging modalities in evaluation of an opaque hemithorax on plain film.