British Journal of Radiology 74 (2001),1003-1006 © 2001 The British Institute of Radiology
Melanoptysis: findings on CT and MRI
J Kirchner, MD1 and
E M Kirchner, MD2
1Klinik für Radiologische Diagnostik und Nuklearmedizin and 2Medizinische Klinik I, Katholisches Marienhospital Herne, Universitätsklinikum der Ruhr Universität Bochum, Hoelkeskampring 40, 44625 Herne, Germany
Correspondence: Priv. Doz. Dr.med. Johannes Kirchner, Department of Diagnostic and Interventional Radiology, Klinikum Niederberg, Akademisches Lehrkrankenhaus, Robert Koch Straße 2, 42549 Velbert, Germany
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Abstract
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The purpose of this study was to demonstrate the CT and MRI features of liquefied progressive massive fibrosis (PMF) in coal worker's pneumoconiosis (CWP). A retrospective analysis was made of the CT and MRI features in five patients suffering from severe CWP with the initial clinical finding of melanoptysis ("black phtisis"). CT showed either an air–fluid level or a fluid–precipitate level with high density in the dependent layer. On pre-contrast T1 weighted images, liquefied PMF showed a fluid level with isointensity relative to soft tissue in the upper layer and a signal loss in the dependent layer of the lesion. The wall of the PMF showed rim enhancement after administration of iv gadolinium. On T2 weighted images there was a high signal intensity in the upper layer of the lesion. In conclusion, liquefied PMF results in characteristic features on CT and MRI owing to precipitation of silica in the mucous fluid.
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Introduction
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In spite of the decline of middle European coal mining industries, with a consequent decrease in the frequency of coal worker's pneumoconiosis (CWP), we are still confronted with radiological findings and complications of this serious occupational disease [1, 2]. One of the subjectively most worrying, but harmless, symptoms of CWP is melanoptysis ("black phtisis"). Black phtisis, the expectoration of large amounts of black-stained sputum, is a result of the liquefaction of a progressive massive fibrosis (PMF). The aim of this paper is to demonstrate the CT and MRI features of liquefied PMF.
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Material and methods
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We evaluated the CT (n=5) and MRI (n=2) appearances in five ex-miners presenting with black phtisis. The mean age of the ex-miners was 73 years (range 66–77 years). The mean duration of occupational exposure ranged between 24 years and 40 years (mean 31.2 years). All were smokers or ex-smokers, with a mean of 58 pack-years (range 47–79 pack-years). The diagnosis of PMF was confirmed by autopsy (n=2) or follow-up examination (n=3). The possibility of cancer or pulmonary tuberculosis was excluded by the absence of significant progression on CT over at least 1 year and negative bronchoscopy.
Contrast enhanced CT was performed on a multislice helical CT machine (Siemens Volume Zoom; Siemens Corp., Forchbeim, Germany) with a tube voltage of 140 kV, a tube current of 120 mAs, 0.5 s rotational time, a collimation of 4 x 2.5 mm and a pitch of 6 (15 mm table feed per rotation). The effective slice thickness of 3–4 mm was reconstructed using a high resolution algorithm. The nature of the lesion itself and the surrounding parenchyma were assessed on the CT images.
MRI of the thorax was performed on a 1.5 T unit (GE Signa; General Electrics Medical Company Europe, Paris, France). T1 weighted enhanced and unenhanced spin echo images (TR 500 ms, TE 14 ms) as well as T2 weighted fast spin echo images (TR 5000 ms, TE 91 ms) were acquired in the axial plane. 0.1 mmol of iv gadolinium-DTPA kg-1 body weight was administered for contrast enhancement. The signal intensity (SI) pattern on the T1 and T2 weighted images was classified as isointense, hypointense or hyperintense compared with muscle, and the SI pattern on T1 weighted images after administration of gadolinium-DTPA was classified as homogeneous enhancement, rim enhancement or absence of enhancement.
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Results
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CT
The CT examinations in all five patients showed eight PMF lesions in total. Three patients showed two symmetrically perihilar lesions. Two patients had only one lesion. All lesions were localized in the upper lobes. The average diameter of the lesions ranged between 2.8 cm and 6.2 cm (median 4.2 cm).
Five of the eight PMF lesions had features of liquefaction. Three of five liquefied PMF lesions showed an air–fluid level (Figure 1
). In four cases there was a precipitate in the dependent layer (Figure 2). There was no evidence of enhancement after iv contrast medium in the necrotic lesion itself. The lateral borders of the PMF were smooth in three lesions and ill defined in five lesions. The medial margins were ill defined in all cases. Irregular perifocal emphysema was seen in all cases and was bullous in two cases. Architectural distortion of the surrounding lung parenchyma was seen in seven lesions and parenchymal bands associated with localized pleural thickening were observed in five lesions. There were no pleural effusions.
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Figure 1. CT of a 69-year-old patient suffering from melanoptysis and severe bullous emphysema owing to coal worker's pneumoconiosis. Notice the air–fluid level within liquefied progressive massive fibrosis of 6 cm diameter. Parenchymal bands associated with local pleural thickening are visible around the lesion. Subcutaneous and mediastinal emphysema are secondary to bronchoscopy.
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Figure 2. CT of a 71-year-old patient suffering from coal worker's pneumoconiosis and melanoptysis. Notice the liquefied progressive massive fibrosis of 3.5 cm diameter in the right upper lobe (posterior segment) demonstrating a fluid level of silicotic material and mucus. A smaller massive fibrosis is seen in the posterior segment of the left upper lobe.
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MRI
MRI was performed in two cases of liquefied PMF. On pre-contrast T1 weighted images, the liquefied PMF showed heterogeneous signal intensity (Figure 3a). There was an isointense signal (relative to soft tissue) in the upper part and signal loss in the dependent part of the lesion. Above this, the lesions were distinguished from the surrounding lung parenchyma by a small high signal outer rim.
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Figure 3. MRI of the same patient as Figure 2 . (a) The unenhanced T1 weighted spin echo image (TR 620 ms, TE 14 ms) of the liquefied progressive massive fibrosis (PMF) demonstrates a heterogeneous signal intensity with isointensity to the muscles in the upper part and signal loss in the dependent part of the lesion. Note the small high signal outer rim of the PMF. (b) A high signal intensity in the upper part of the lesion on the T2 weighted image (single shot fast spin echo/90 with TR>20 000 ms, TE 94 ms).
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There was peripheral rim enhancement on contrast enhanced T1 weighted images.
On T2 weighted images the dependent parts of the liquefied PMF were indistinguishable from the surrounding aerated lung parenchyma, but showed a high signal intensity in the upper parts of the lesion (Figure 3b).
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Discussion
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Pathological specimens in CWP commonly demonstrate a combination of silico-related fibrosis and deposition of other materials such as anthracotic particles. The local mixture of inhaled dusts results in differences in the clinical course of the disease and in the radiological appearances. Nevertheless, the 2–4 mm diameter silico-granuloma is the common building block of all forms of the silico-induced lung fibrosis.
The confluence of many granulomas results in a fibrotic lesion. A lesion more than 1 cm in its greatest diameter is termed massive fibrosis or, if it shows increasing growth, PMF [1, 2]. The centre of the PMF often shows necrotic areas with liquefaction of the necrotic masses. Cavitation may occur and the liquid material is expectorated if the necrosis reaches the bronchial tree. This symptom is called black phtisis or melanoptysis.
The term "melanoptysis" is derived from the Greek adjective melas, meaning black, and the noun ptysma, meaning spit. It is also called "Phtisis atra", from the Latin adjective ater, which means dark [3]. The radiological diagnosis becomes more difficult in patients presenting with melanoptysis, and silicotuberculosis and scar cancer, or other malignancy, may be considered [4, 5].
While the findings of PMF an chest radiography and CT have been well described [4, 6–8], only two studies on very few patients have described the MRI appearance of PMF [9, 10], with conflicting findings. Matsumoto et al [10] reported the most common MRI findings in PMF to be signal isointensity on T1 weighted images and hypointensity on T2 weighted images compared with muscle. These authors did not find any signal increase or rim enhancement after iv gadolinium. In contrast, Jung et al [9] reported PMF to show a high signal intensity on T1 weighted images relative to soft tissue in the majority of cases (14 of 18). A significant signal enhancement after iv gadolinium was observed in all cases. The lesions were described as being of low signal intensity on T2 weighted images and only distinguishable from the surrounding aerated lung parenchyma owing to a small high signal outer rim.
Jung et al [9] mentioned that two cases of their own study group showed a high signal intensity on T2 weighted images in the centre of a PMF lesion, suspicious of liquefaction. Nevertheless, until now there has been no description of MRI findings in liquefied PMF as seen in cases of black phtisis.
The reason for the heterogeneous MRI signal intensity in the centre of the liquefied PMF lesion is uncertain but may be explained by the different types of fluid that have been found at autopsy. The comparison of our findings in CT and MRI support the following hypothesis. The opacity in the dependent layer of the liquefied PMF seen on CT possibly represents precipitated silica. This precipitate decreases the proton density and results in a very low signal intensity on both T1 and T2 weighted images. Additionally the signal loss in the dependent layer, especially on non-refocused gradient echo (GRE) sequences, may be accentuated by the different susceptibility between the precipitated silica and the surrounding aereated lung parenchyma. The fluid in the non-dependent layer of the lesion possibly represents proteinous mucus. Because the increase in the protein content of a fluid shortens its T1 relaxation times [11], the fluid layer may have a signal intensity higher than shown by pure fluid on the T1 weighted images.
Our findings in five patients illustrate that liquefied PMF results in typical findings on both CT and MRI. If PMF is regarded as the vacuum cleaner of the coal workers lung, the dense opacity in the dependent layer represents the dust in the cleaner bag.
Received for publication March 22, 2001.
Revision received July 4, 2001.
Accepted for publication July 10, 2001.
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Abstract
Introduction
