AJR 2002; 178:949-951
© American Roentgen Ray Society
Malignant Pleural Mesothelioma with Osteoblastic Heterologous Elements
CT and MR Imaging Findings
Géraldine Chave1,
Lara Chalabreysse2,
Georges Picaud1,
Nadine Blineau1,
Robert Loire2,
Françoise Thivolet2,
Yves Berthezène1,
C. Philippe Douek3 and
Bruno Marchand1
1
Department of Radiology, Hôpital de la Croix-Rousse, 103 Grande Rue de
la Croix-Rousse, 69317 Lyon Cedex, France.
2
Department of Pathology, Hôpital Cardiovasculaire et Pneumologique Louis
Pradel, 28 Ave. Doyen Lépine, 69500 Bron-France.
3
Department of Radiology, Hôpital Cardiovasculaire et Pneumologique Louis
Pradel, 69500 Bron-France.
Received December 13, 2000;
accepted after revision September 6, 2001.
Address correspondence to B. Marchand.
Introduction
Malignant pleural mesothelioma is a rare primary tumor of the pleura,
strongly linked to asbestos exposure
[1]. The microscopic features
have been characterized according to three main groups, including the
epithelioid, sarcomatoid, and biphasic forms
[1]. Malignant pleural
mesothelioma with osteoblastic heterologous elements, previously classified as
malignant pleural mes-othelioma with osseous differentiation
[2], is an extremely rare
histologic subtype. Few cases of this particular tumor have been described in
the literature, to our knowledge, with only 10 cases reported on the basis of
chest radiographs [3] and only
three cases reported on the basis of CT findings
[4,
5]. We present a histologically
proven case of malignant pleural mesothelioma with osteoblastic heterologous
elements, shown on CT and MR imaging.
Case Report
A 59-year-old man, with a history of smoking and asbestos exposure,
complained of right chest pain. A chest radiograph showed a right pleural
effusion associated with a focal pleural thickening. An initial enhanced CT
scan (Fig. 1A) revealed a right
focal pleural thickening. A pleural biopsy was performed with video-assisted
thoracoscopy. Histologically, the examination revealed a growth pattern
composed of epithelial cells and a sarcomatous component composed of malignant
spindle cells (Fig. 1B).
Histochemically, keratin stains were positive for epithelial cells, whereas
spindle cells expressed both keratin and vimentine. Therefore, a malignant
pleural mesothelioma was diagnosed. The patient underwent intrapleural
treatment with gamma interferon.
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Fig. 1A. —59-year-old man with malignant pleural mesothelioma with
osteoblastic heterologous elements. Initial unenhanced CT scan (lung window
setting) shows right focalized pleural thickening (long arrow) with
no calcification. Air (short arrow) in pleural thickening is related
to prior puncture.
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Fig. 1B. —59-year-old man with malignant pleural mesothelioma with
osteoblastic heterologous elements. Photomicrograph of initial histologic
specimen obtained from pleural biopsy using thoracoscopy shows biphasic
pleural tumor with epithelial component (arrowhead) intermingled with
spindle cells (arrow). (H and E, x40)
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Three years later, he was admitted for Pancoast-Tobias syndrome. Because of
a severe anaphylactic reaction after injection of an iodinated contrast agent,
unenhanced CT was performed, revealing that the focal pleural thickening
depicted 3 years previously had increased in size and that pleural
calcifications had appeared (Fig.
1C). We obtained an MR image to evaluate better the apical
extension of the tumor and because of a superior vena cava syndrome. The MR
imaging sequences included both T1- and T2-weighted axial images and fast
spin-echo fat-saturated T2- weighted images in the coronal plane (Figs.
1D and
1E). MR imaging confirmed the
apical extension of the tumor. The tumor presented areas of bright signal in
T2-weighted images and calcified areas with no signal in both T1- and
T2-weighted images. A pleural biopsy compared with the biopsy performed 3
years earlier revealed that the sarcomatous pattern was composed of foci of
malignant osteoid tissue (Fig.
1F). Therefore, a malignant pleural mesothelioma with osteoblastic
heterologous elements was diagnosed. Palliative treatment was performed before
the patient died 3 years after the initial diagnosis.
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Fig. 1C. —59-year-old man with malignant pleural mesothelioma with
osteoblastic heterologous elements. Unenhanced CT scan (mediastinal window
setting), obtained 3 years later at same level as A, shows increase in
pleural thickening spreading into chest wall (arrow) associated with
two coarse calcifications (arrowheads) that were situated close to
mediastinal pleura and into right paratracheal space. These calcifications may
be due to direct tumoral extension, because of their continuity with mass,
although it is not possible to formally exclude enlarged calcified lymph node
in region 4R.
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Fig. 1D. —59-year-old man with malignant pleural mesothelioma with
osteoblastic heterologous elements. Unenhanced axial T1-weighted MR image
displays chest wall and apical extension by tumor (arrow) and pleural
calcifications with no signal (arrowheads).
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Fig. 1E. —59-year-old man with malignant pleural mesothelioma with
osteoblastic heterologous elements. Unenhanced coronal short tau
inversion-recovery MR image reveals calcified areas with no signal
(arrow) and remainder of tumor with bright signal
(arrowhead) spreading into chest wall and lung apex.
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Fig. 1F. —59-year-old man with malignant pleural mesothelioma with
osteoblastic heterologous elements. Photomicrograph of histologic specimen
obtained from pleural biopsy 3 years after B reveals highly malignant
proliferation of poorly differentiated tumoral cells of epithelioid type with
osteoid tissue (arrowhead). (H and E, x25)
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Discussion
Malignant pleural mesothelioma with osteoblastic heterologous elements,
previously classified as malignant pleural mesothelioma with osseous
differentiation [2], rarely
occurs in malignant pleural mesothelioma, with only 13 cases previously
reported
[3,4,5].
Patients with this condition commonly had a history of asbestos exposure and
tended to be 60 years old or older
[3,4,5].
Clinically, patients tended to present with shortness of breath (11/13 cases)
and back or chest pain (six cases), whereas weakness or loss of weight (two
cases) and hemoptysis (one case) were rarely reported
[3,4,5].
A bloody pleural effusion was found in eight patients. When available, the
record of clinical evolution was mainly characterized by a rapid deterioration
of pulmonary function and by the spreading of the tumor into the lung.
Histologically, malignant pleural mesothelioma is associated with three
histologic subgroups: the epithelioid, sarcomatoid, and biphasic forms. The
epithelioid from corresponds to approximately two thirds of malignant pleural
mesothelioma. It is difficult to distinguish the epitheloid form of malignant
pleural mesothelioma from metastatic adenocarcinoma of the pleura
[1,
3]. The sarcomatoid form
represents nearly 10-15% of malignant pleural mesothelioma, including several
variants such as desmoplastic and fibrosarcomatous patterns. The biphasic
group shows a mixed histologic pattern, corresponding to nearly 20-30% of
malignant pleural mesothelioma. Histochemical findings are useful in
distinguishing these three subgroups. Schematically, tumoral cells express
keratin in the epitheloid form, vimentine in the sarcomatoid form, and both in
the biphasic form [1,
3]. Osteoblastic elements may
be present in malignant pleural mesothelioma, sometimes in a
myxoid—chondroid mixed matrix
[3,
4]. Osteoid elements show
mineralization, and when neoplastic cartilage is present, enchondral
ossification is observed in nearly all the cases
[3,
5].
Chest radiographs commonly show diffuse pleural effusion associated with
focal or diffuse thickening of the pleura. Similar to findings in typical
cases of malignant pleural mesothelioma, in malignant pleural mesothelioma
with osteoblastic elements, CT scans show pleural effusion associated with
diffuse thickening of the pleura or localized pleural masses. Only Raizon et
al. [5] reported a coarse focal
calcified mass adjacent to the pleura in two histologically proven cases of
malignant pleural mesothelioma with osteoblastic elements. This finding is
consistent with our patient, who presented two particular features on CT
scans: calcifications of the pleura were multiple with one arising from the
mediastinum pleura and spreading into the right paratracheal area; pleural
calcifications were increased during the follow-up period of 2 years,
reflecting osteoid mineralization by the tumor.
To our knowledge, MR imaging findings of malignant pleural mesothelioma
with osteoblastic elements have not been reported in the literature. In the
our patient, a clinically suspected superior vena cava syndrome was excluded
by MR imaging findings. MR images showed large masses of the pleura with no
signal in both T1- and T2-weighted images, corresponding to areas of
calcification. Axial T1-weighted and coronal T2-weighted images showed the
spreading of the tumor into the chest wall and the apex. Furthermore,
noncalcified portions of the tumor presented a bright signal on T2-weighted
images. Falaschie et al. [6]
reported that a bright signal in pleural masses on long-TR MR images favored
pleural malignancies.
Commonly, the clinical course leads to a fast deterioration of pulmonary
function related to progressive pleural and lung disease. Yousem and Hocholzer
[3] reported that nine of 10
patients died within 1 year, with an average length of survival from time of
diagnosis of 5.7 months. Metastases were sometimes located in the pericardium
[3,
5], whereas parenchymal lung
metastases were absent. Our patient had an unusually long clinical course,
with a 3-year follow-up period from the time of the initial diagnosis.
Although pleural calcification is usually considered to be highly
suggestive of benign disease
[7], pleural calcification may
occur rarely in the malignant pleural mesothelioma with osteoblastic
heterologous elements, primitive or secondary osteogenic sarcoma of the
pleura, and chondrosarcoma of the pleura. A primary intrathoracic extraosseous
osteogenic sarcoma of the pleura may be difficult to differentiate from a
malignant pleural mesothelioma with osteoblastic heterologous elements
[3,
8]. In primary intrathoracic
extraosseous osteogenic sarcoma, gross pathologic findings may also show a
calcified mass contiguous to the pleura. In contrast to the malignant pleural
mesothelioma with osteoblastic heterologous elements, in primary intrathoracic
extraosseous osteogenic sarcoma, no history of asbestos exposure is found, and
tumoral cells do not express keratin.
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Introduction
Case Report
