Pleural plaques: imaging findings and localization
Pleural changes associated with asbestos exposure are most commonly located in the lower chest and along the diaphragmatic pleura. When the involvement is extensive, the pathological process may spread to the anterior and lateral chest walls.
Morphologically, such plaques frequently undergo calcification or even ossification.
Imaging modalities:
- Chest X-ray (CXR): plaques are well visualized if they have reached a large size and show signs of calcification.
- Computed tomography (CT): on axial and coronal slices, the lesions appear as pronounced, high-density pleural thickenings.
Pleural tumors: classification
Pleural neoplasms (Pleural Tumours) are conventionally classified according to three main criteria:
- By extent: diffuse or localized.
- By growth pattern: malignant or benign.
- By origin: primary or secondary (metastases).
Epidemiologically, localized variants are quite rare. The absolute majority of neoplasms in this location are diffuse malignant tumors.
Solitary fibrous tumor of the pleura
Pleural fibroma (synonym: Solitary fibrous tumour of the pleura, SFTP) is a localized lesion that typically manifests in middle age. Interestingly, in about half of the patients, the disease is completely asymptomatic.
Approximately two-thirds (2/3) of these tumors have a benign structure, while the remaining third (1/3) are malignant.
Characteristic syndromes and complications include:
- Hypertrophic osteoarthropathy (HPOA) — a classic complication recorded in 10–30% of patients.
- Hypoglycemia — rare, but an important marker.
Imaging features of pleural fibroma
On chest radiography, the fibroma appears as a pleural-based mass with clear margins. The shape is usually rounded and slightly lobulated. The lesion forms an obtuse angle with the chest wall and can vary in size from 2 to 20 cm, occasionally reaching giant proportions. An important radiological sign is the presence of a pedunculation (stalk), which allows the tumor to shift significantly with respiration or changes in body position.
Typical locations of fibroma (most often in the lower third of the chest):
- Thoracic (costal) pleura — 46%
- Interlobar fissure — 30%
- Mediastinal pleura — 18%
- Area adjacent to the diaphragmatic dome — 6%
On CT, the appearance largely mirrors the radiographic findings, but allows for a more detailed evaluation of the structure. Due to areas of hemorrhage and necrosis, the internal structure is frequently heterogeneous. Calcifications may be present. Following intravenous contrast administration, it shows characteristic contrast enhancement with a swirling pattern.
Briefly: answers to topical questions
Which CT features indicate malignancy in a solitary fibrous tumor of the pleura?
Malignant variants of solitary fibrous tumor of the pleura (pleural fibroma) are identified by large size, signs of local invasion, and the presence of associated complications.
- Large size — lesions typically exceed 10 cm in diameter.
- Invasive growth — the tumor may invade directly into the chest wall.
- Dissemination — capable of metastasizing to the pleura or lungs.
- Presence of fluid — may be accompanied by pleural effusion.
What are the histological types of malignant pleural mesothelioma?
There are three histological subtypes of malignant pleural mesothelioma:
- Epithelioid mesothelioma — accumulates FDG less intensely than the sarcomatoid type.
- Sarcomatoid mesothelioma — accumulates FDG more intensely than the epithelioid type.
- Biphasic subtype — diagnosis is challenging due to significant overlap of characteristics.
Class and exam questions
Why might pleural fibroma change its position on radiographs?
Due to the presence of a specific stalk (pedunculation), the lesion is mobile and can shift with changes in patient position or during respiratory movements.
What are pleural plaques most commonly associated with?
They are associated with long-term exposure to asbestos in the body.
What does pleural fibroma look like on contrast-enhanced CT?
It is characterized by heterogeneous contrast enhancement in the form of a swirling pattern, while the structure itself is often heterogeneous due to necrosis and hemorrhage.
What else to study on this topic
- Pathogenesis of hypertrophic osteoarthropathy in pleural fibroma
- Differential diagnosis of malignant and benign fibromas
- Histological features of solitary fibrous tumor
- Causes of hypoglycemia in pleural neoplasms
- Recognizing the "swirling" pattern on CT scans
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