E W Paterson, A D Chapman O J Dempsey
Department of Respiratory Medicine, Chest Clinic, Aberdeen Royal Infirmary, AB24 5EZ.
Correspondence to Dr O J Dempsey, Consultant Chest Physician, Aberdeen Royal Infirmary., AB24 5EZ. Telephone: 01224 552320
Email: owen.dempsey@nhs.net
SMJ 2006 52(1): 55
Abstract
Endobronchial metastases should be considered in the differential diagnosis of an endobronchial mass. This case report describes an endobronchial presentation of malignant melanoma. The importance of immunohistochemistry techniques in securing a diagnosis are discussed.
Case Report
Patients are commonly referred to Respiratory Physicians because a “mass” is evident on their chest radiograph. If there is a smoking history, the diagnosis is usually lung cancer. In this case report, we describe a patient presenting similarly, with a surprising diagnosis and discuss the clinical lessons learned.
A sixty seven year old man presented to the Accident and Emergency Department with sudden onset, anterior, sharp right-sided chest pain. This lasted one hour before settling spontaneously. He also had a two month history of dry cough. There were no other symptoms such as weight loss, breathlessness or haemoptysis. Past medical history was remarkable only for essential hypertension, treated with amlodipine. He was an ex-smoker with a 30-cigarette pack year history and previously worked as a technician in a nuclear power station. Clinical examination was normal. A chest radiograph showed a left hilar mass and he was referred to our service for further assessment. The working diagnosis was bronchial carcinoma.
At fibre-optic bronchoscopy, a necrotic mass was seen in left upper lobe and subsequent endobronchial biopsies confirming “malignancy.” Further classification was not possible because of the small sample size. “Non-small cell bronchial carcinoma” was suggested as the most likely provisional diagnosis, but further immunohistochemistry was organised to clarify this. Computerised tomography of thorax and upper abdomen confirmed a 22 x 22 mm left apical mass, with central necrosis, in the anterior segment of the left upper lobe, and also a 10mm left hilar lymph node. Blood and pulmonary function tests were normal. Therefore, he was referred to the Thoracic Surgical service for mediastinoscopy to stage his mediastinal lymphadenopathy.
On the morning of his planned mediastinoscopy, immunohistochemistry results became available, and were surprisingly consistent with malignant melanoma. His mediastinoscopy was cancelled. A more detailed examination of his skin followed, and a small, partially pigmented, warty lesion was identified behind his right ear. This was excised and subsequent histopathology confirming malignant melanoma. No lesions were evident elsewhere clinically, although positron emission tomography confirmed extensive secondary disease affecting left lung, both hilae, right neck nodes, right axilla, upper left arm and penis. He was subsequently treated with cisplatinin and dacarbzine chemotherapy but died seven months later.
Discussion
Primary bronchial malignant melanoma is rare and such a diagnosis can only be made in the absence of convincing evidence of a primary lesion.1 It is much more likely that the endobronchial lesion seen in our patient represented a metastatic deposit. Approximately 10% of patients with malignant melanoma will have metastases at presentation. Metastases have been described in lung, liver, brain and bone and less commonly in bowel, kidney and muscle. Spread to the bronchial tree is unusual, but has been reported.2
What clinical lessons can be learned from this case? Endobronchial metastases, while uncommon, do occur and should be considered in the differential diagnosis of any patient presenting with an endobronchial mass.3 Clinical examination should be comprehensive and include the skin. Immunohistochemistry can be invaluable in confidently securing a tissue diagnosis, and newer imaging modalities such as positron emission tomography play an increasingly important role in the staging of malignant disease.
Figure I
a) Chest radiograph noting left hilar mass. b) Coronal FDG-PET image, showing multiple sites of FDG uptake(arrows) including left lung mass, lymph nodes in right cervical region, right axilla , both hila, and proximal right humerus. Normal myocardial uptake is also seen.
Figure II
Bronchial biopsy showing discohesive malignant cells with eosinophilic cytoplasm and occasional prominent nucleoli.
Inset: positive S100 immunohistochemical stain confirming diagnosis of melanoma.
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