A 64-year-old Asian man reported dyspnea on exertion over the prior few weeks, which was progressively getting worse. The patient had a right-sided thoracentesis a year previously at an outside hospital and was told that he had a “spot” in his right lung. Upon examination, he was afebrile and his oxygen saturation was 74% on room air.
A 64-year-old Asian man reported dyspnea on exertion over the
prior few weeks, which was progressively getting worse. The patient
had a right-sided thoracentesis a year previously at an outside
hospital and was told that he had a "spot" in his right lung. Upon
examination, he was afebrile and his oxygen saturation was 74% on
room air. Physical examination was positive for digital clubbing,
and auscultation of the right lung revealed a complete lack of
breath sounds. The patient admitted to a 50-pack/year smoking
history prior to quitting 20 years previously but denied any weight
loss or night sweats. Complete blood count and basic metabolic
panel were within normal limits.
Benign solitary fibrous tumor originating from the parietal
Upon admission into the emergency department, chest X-ray
revealed complete opacification of the right hemithorax with
mediastinal shift to the left (Figure 1). An attempt at
thoracentesis was unsuccessful for the retrieval of fiuid. A
subsequent contrast-enhanced chest computedtomography (CT) scan
revealed a very large, well-encapsulated, heterogeneous mass in the
right hemithorax that was compressing the right main stembronchus
and pushing the mediastinum to the left (Figure 2). CT also showed
an associated right pleural effusion. Radiographically, solitary
fibrous tumors of the pleura (SFTP) tend to appear as
well-demarcated, solitary, enhancing masses that form obtuse angles
with the chest wall or mediastinum. They are more often found in
the middle and lower aspects of the chest. Calicifications (~5%)
and pleural effusions (~8% to17%) are uncommon.
A multiplanar, multisequence contrast-enhanced magnetic
resonance image (MRI) was obtained, confirming the findings of the
chest CT. In addition,there was no evidence of invasion of the
chest wall (Figure 3). Solitary fibrous tumors of the pleura
usually exhibit low signal characteristics on T1- and T2-weighted
images (T2WI), indicative of fibrosis. However, high signal on T2WI
can represent areas of necrosis or hemorrhage.
The imaging findings warranted a biopsy and surgical resection
(Figure 4). The patient was brought to the operating room and
underwent resection of the tumor and wedge resection of the right
middle and right lower lobes. The mass was adherent to the chest
wall, without any evidence of mediastinal invasion.
Solitary fibrous tumors of the pleura are very rare,slowly
growing tumors and represent <5% of alltumors involving the
As of 2001, approximately 600 cases had been reported in the
Solitary fibrous tumors of the pleura generally occur in patients
>50 years of age. One study conducted over an 18-year period at
Memorial Sloan-Kettering Cancer Center (MSKCC) found a positive
association between malignancy and a tumor size >10 cm.
In the past, there was some mystery as to the histiogenesis of
SFTP. It was thought that these tumors were related to
mesotheliomas. Also, at one time, SFTPs were called by different
names, such as benign or localized mesothelioma, benign fibrous
mesothelioma, and subpleural fibroma.
However, they have no established relationship to asbestos exposure
or smoking, and their origin has been revealed as submesothelial
mesenchymal cells (presence of fibroblasts with negative staining
Solitary fibrous tumors of the pleura originate from either the
visceral or parietal pleura; the former are more common. Most
(>80%) SFTPs are benign. However, both benign and malignant
types should be completely excised because of their growth
potential. Malignant SFTPs have a greater chance of local
recurrence and metastasis. If not completely excised, the malignant
form may recur years after excision, whether the original SFTP was
benign or malignant. Solitary fibrous tumors of the pleura have
rarely been known to metastasize.
Malignant tumors include at least one of the following
: 1) High mitotic count [>4 mitosis/10 HPF (×400)]; 2) presence
of a large area of necrosis; 3) nuclear crowding and overlapping;
and 4) nuclear atypia. The number of mitoses tends to be the best
indicator of malignancy.
The best prognostic factors are encapsulation, pedunculation, and
Solitary fibrous tumors of the pleura have no gender
predilection and are often incidental findings on chest X-ray.
However, patients can become symptomatic, presenting with chest
pain, dyspnea, cough, hypertrophic osteoarthropathy, digital
clubbing, and hypoglycemia. There is no relationship between the
size of the tumor and the presence of hypertrophic osteoarthropathy
and digital clubbing. Hypoglycemia occurs because SFTPs may secrete
Solitary fibrous tumors may also arise in the pericardium,
mediastinum, pancreas, or paranasal sinuses.
Since no current imaging modality can distinguish between the
benign and malignant forms, biopsy is indicated. Often the biopsy
will be inconclusive, revealing only disorganized spindle cells.
When adequate samples are obtained, they stain positive for
and negative for cytokeratin. Since imaging studies and biopsies
are usually equivocal for the presence of malignancy, every
suspected SFTP should be surgically removed.
Solitary fibrous tumors of the pleura are slow-growing tumors
that are not histologically related to mesotheliomas. Most of these
tumors are benign, but regardless of their categorization, total
surgical excision is indicated and likely diagnostic. Complete
resection is the best prognostic factor.
Those who have undergone surgery should receive yearly follow-up CT
scans to rule out recurrence. For most, recurrence does not occur
(regardless of histologic classification), and surgical excision is
curative. However, recurrence can occur from either a benign or
malignant initial SFTP. Neither postoperative chemotherapy nor
radiotherapy has been shown to be required.
What makes this case of SFTP even more rare is its benign
diagnosis as such a large tumor (>>10 cm), its parietal
pleural basis, and the presence of a pleural effusion.