Eur J Cardiothorac Surg 2005;28:655-656
© 2005 Elsevier Science NL
Pseudomesothelioma resulting from metastatic malignant melanoma
Heyman Luckraz
a
,
*
,
Matt Morgan
a
,
Allen R. Gibbs
b
,
Eric G. Butchart
a
a Cardiothoracic Unit, Block C5, University Hospital of Wales, Heath Park, Cardiff CF14 4XN, UK
b Histopathology Department, University Hospital of Wales, Heath Park, Cardiff CF14 4XN, UK
Received 22 March 2005;
received in revised form 19 May 2005;
accepted 23 May 2005.
* Corresponding author. Tel.: +44 2920 743578; fax: +44 2920 745439. (Email: heymanluckraz{at}aol.com).
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Abstract
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Isolated pleural metastatic melanoma is an uncommon clinical condition. Clinical diagnosis can be difficult and therapeutic options are limited. We describe a case where there was isolated pleural metastasis, 10 years following complete excision of a superficial melanotic lesion, which presented like a malignant mesothelioma (‘pseudomesothelioma’).
Key Words: Pleural melanoma • Pseudomesothelioma
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1. Introduction
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Rarely tumours can metastasise and spread diffusely within the pleura to form an encasing mass which clinically, radiologically and pathologically mimics malignant mesothelioma. A recent review of ‘pseudomesotheliomatous carcinomas’ of the pleura described 53 cases, the most frequent being primary adenocarcinoma of the lung which comprised 72% and small numbers of other primary lung carcinomas [1]. No case of malignant melanoma was included. Other non-carcinomatous tumours which can grow diffusely within the pleura to simulate mesothelioma have included malignant vascular tumours, synovial sarcoma, thymoma and malignant lymphoma.
Intra-thoracic metastasis from melanoma, a malignancy of pigment-producing cells (melanocytes), is well documented in the literature but usually involves the lung parenchyma and rarely the parietal pleura in conjunction with a lung parenchymal lesion. We describe a case of malignant melanoma which metastasized solely to the parietal pleura of the hemithorax ipsilateral to the original site of the malignant melanoma and spread diffusely to mimic the growth pattern of malignant mesothelioma.
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2. Case report
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A 64-year old lady was referred for further management following recurrent episodes of right sided pleural effusions over a period of 3 months. This was associated with a loss of appetite and a 5Kg loss in weight. She had been a 50-pack year smoker until the development of shortness a breath which was due to the pleural effusion.
Clinically and roentgen graphically there was a significant right-sided pleural collection. There was no evidence of lymphadenopathy or hepatomegaly. CT scan of the chest confirmed the presence of pleural effusion and also revealed nodular thickening of the right parietal pleura (Fig. 1
). There was no past history of exposure to asbestos but the patient did have a malignant melanoma skin lesion excised from her right upper arm, 10 years ago. The histology was a superficial spreading melanoma to a depth of less than 1mm, completely excised and with no evidence of lymphatic extension.
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Fig. 1. CT scan of the thorax showing a right-sided pleural effusion and nodular thickening (NT) of the parietal pleura posteriorly.
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The cytological and biochemical analysis of pleural aspirate prior to surgical referral revealed small lymphocytes but no malignant cells. The differential diagnosis included mesothelioma and all those conditions which mimic this pleurotropic growth namely adenocarcinoma, lymphoma, primary pleural sarcoma, thymic epithelial tumors and metastatic tumors (in this case melanoma).
She underwent a right postero-lateral thoracotomy with a view to performing a pleurectomy and decortication. This revealed a straw colored pleural effusion (500ml) and the parietal pleura was loosely adherent to the visceral pleura. A parietal pleurectomy was performed and there were multiple pigmented nodular deposits on the parietal pleura (Fig. 2
) but not on the visceral pleura. There were no intrapulmonary metastases.
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Fig. 2. Photograph of the resected parietal pleura measuring 150x100mm and showing multiple pigmented nodules of varying sizes.
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Histological analysis of the resected specimen confirmed the deposits to be malignant melanoma composed of epithelioid cells which mimicked epithelioid malignant mesothelioma. Immuno-staining showed the tumour to be positive for HMB45 and S100 and negative for calretinin and CK 5/6. She made an uneventful post-operative recovery and is now undergoing oncological treatment.
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3. Discussion
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Although primary pleural melanoma has been previously described [2] it remains an extremely rare and controversial entity. Moreover, secondary metastatic pleural melanoma is also very uncommon and usually occurs in the setting of concomitant pulmonary metastasis [3,4]. Isolated pleural malignant melanoma metastases have not been reported previously.
The radiological patterns described in thoracic melanoma metastases include most commonly either multiple (40%) or solitary (20%) pulmonary nodules. Rare presentations in this group include a miliary pattern, mediastinal lymphadenopathy, pleural effusions, lytic bone lesions and extra-pleural mass.
The prognosis of malignant melanoma is variable with distant metastases sometimes occurring more than 10-years after initial therapy. The most powerful predictors of survival are tumor thickness and ulceration. The initial skin lesion was less than 1mm in thickness with no ulceration, a tumor with intermediate prognosis with an expected 5-year disease free survival of up to 90% [5]. This highlights the unpredictable behavioural nature of a small proportion of malignant melanomas.
This case highlighted the common clinical and radiological presentations of mesothelioma and the pseudomesotheliomas with similarities even at macroscopic and microscopic level. Accurate diagnosis is important for prognostic, treatment and medico-legal purposes and relies on immunocytochemistry [1] and relies on the demonstration of intracellular melanin and immunohistochemical procedures since light microscopically both mesothelioma and melanoma can show epithelioid, spindle cell and biphasic patterns. The prognosis of the majority of pseudomesotheliomatous tumours is poor and similar to mesotheliomas but there are some exceptions such as malignant lymphomas and thymomas which show longer survivals with appropriate treatment. The prognosis of ‘pseudomesotheliomatous’ malignant melanoma is uncertain.
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References
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- Attanoos RL, Gibbs AR. ‘Pseudomesotheliomas’ carcinoma of the pleura; a 10-year analysis of cases from the Environmental Lung Disease Research Group. Cardiff Histopathol 2003;43:444-452.[CrossRef]
- Smith S, Opipari MI. Primary pleural melanoma. A First reported case and literature review. J Thorac Cardiovasc Surg 1978;75:827-831.[Abstract]
- Chen JT, Dahmash NS, Ravin CE, Heaston DK, Putman CE, Siegler HF, Reed JC. Metastatic melanoma in the thorax: report of 130 patients. Am J Roentgenol 1981;137:293-298.[Abstract/Free Full Text]
- Kiser AC, Egan TM. Metastatic melanoma to the pleural space. Ann Thorac Surg 2002;74:1257.[Free Full Text]
- Balch CM, Soong SJ, Gershenwald JE, Thompson JF, Reintgen DS, Cascinelli N, Urist M, McMasters KM, Ross MI, Kirkwood JM, Atkins MB, Thompson JA, Coit DG, Byrd D, Desmond R, Zhang Y, Liu PY, Lyman GH, Morabito AI. Prognostic factors analysis of 17,600 melanoma patients: validation of the American Joint Committee on Cancer melanoma staging system. J Clin Oncol 2001;19:3622-3634.[Abstract/Free Full Text]
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Abstract
1. Introduction
