CASE REPORT
European Journal of Cardio-Thoracic Surgery 46 (2014) 919–920 doi:10.1093/ejcts/ezu105 Advance Access publication 17 March 2014
Hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin Kentaro Miura, Takashi Eguchi*, Gaku Saito and Kazuo Yoshida Division of Thoracic Surgery, Shinshu University, Matsumoto, Japan * Corresponding author. Division of Thoracic Surgery, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan. Tel: +81-263-372657; fax: +81-263-372721; e-mail: [email protected] (T. Eguchi). Received 16 December 2013; received in revised form 7 February 2014; accepted 18 February 2014
Abstract We report a case of hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin. A left pulmonary nodule was detected during a check-up in a 58-year old woman. Chest computed tomography indicated a large left hilar mass located between the upper and lower lobes. She underwent left pneumonectomy with mediastinal lymph node dissection, and the tumour was diagnosed as hilar lymph node metastasis of an amelanotic malignant melanoma; however, the primary lesion could not be detected. Thus, the possibility of spontaneous regression of the primary lesion and the amelanotic subtype of malignant melanomas should be considered in clinical practice.
INTRODUCTION Malignant melanoma is a cancer with a high associated mortality rate. Malignant melanomas generally originate from the skin and commonly metastasize to the lung. Although melanoma can also originate from the lung, such cases are extremely rare. Amelanotic malignant melanoma is a rare subtype of malignant melanoma, where little or no pigmentation is noted on visual inspection. Amelanotic malignant melanoma reportedly accounts for 1.8–8.1% of all cases of malignant melanomas [1, 2]. In the present report, we describe a case of hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin, for which left pneumonectomy was performed.
CASE A left pulmonary nodule was detected on chest computed tomography (CT) in a 58-year old woman during a check-up. She did not have any history of major disease or any specific cancer-related familial history. Chest radiography indicated the presence of a large mass shadow in the left hilum. Chest CT further indicated a large hilar mass, 42 × 34 × 50 mm in size, between the left upper and lower lung lobes (Fig. 1). The left upper and lower bronchi and interlobar pulmonary artery were adjacent to and displaced by the tumour. 18F-fluorodeoxyglucose–positron emission tomography (FDG–PET) performed 1 month after tumour detection showed high FDG accumulation in the tumour. The maximum standardized uptake value was found to be 9.3, and no abnormal accumulation at any other site. Based on the findings of transbronchoscopic lung aspiration cytology, the tumour was diagnosed as malignant; however, it was difficult to histologically diagnose the tumour based on the aspiration cytology findings.
The patient’s lung function parameters were as follows: forced vital capacity, 3050 ml and 120% of the predicted value; forced expiratory volume in 1 s, 2350 ml; percentage of predicted carbon monoxide diffusion lung capacity, 104%. No definitive preoperative diagnosis was established; however, we decided to perform radical resection of the left hilar tumour as CT and FDG–PET showed no signs of involvement at other sites and the patient had adequate lung function. During surgery, a large mass was detected between the interlobar pulmonary artery and the left upper and lower bronchi. Hence, we determined that radical surgery could not be achieved because of inadequate margins if we were to preserve either the left upper lobe or the left lower lobe. Thus, left pneumonectomy with systematic mediastinal lymph node dissection was performed according to the standard node dissection for lung cancer surgery (ND2a-1). Intrathoracic left superior and inferior pulmonary vein dissection was difficult because of compression by the bulky hilar tumour and, therefore, these vessels were dissected and divided intrapericardially. A subsequent pathological examination indicated the presence of a non-pigmented white tumour consisting of proliferating epithelioid and spindle cells, with a large round nucleus containing prominent eosinophilic nucleoli (Fig. 2A and B). Moreover, certain lymph node components were also detected around the tumour tissue on histological examination. No nodular lesions were noted in the left lung parenchyma. No metastasis to the mediastinal lymph nodes was diagnosed. On immunohistochemical staining, the tumour cells yielded positive results for MART-1 and S100, but negative results for HMB45 (Fig. 2C). Thus, the tumour was eventually diagnosed as hilar lymph node metastasis of an amelanotic malignant melanoma of unknown origin. The primary lesion could not be detected by postoperative systemic examinations. The patient’s postoperative course was uneventful, and she has been followed up for 2 years without any evidence of recurrence.
© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
CASE REPORT
Keywords: Amelanotic malignant melanoma • Lymph node metastasis • Pneumonectomy
920
K. Miura et al. / European Journal of Cardio-Thoracic Surgery
Figure 1: Chest computed tomography images (A, axial section; B, sagittal section) showing a large hilar mass located between the left upper and lower lung lobes.
Figure 2: (A) Section of the left lung indicating a non-pigmented white tumour. (B) Analysis of the tumours under high magnification (haematoxylin and eosin staining; original magnification ×500) showing proliferating epithelioid cells with a large round nucleus containing prominent eosinophilic nucleoli. (C) Immunohistochemical staining showing that the tumour cells were positive for MART-1.
DISCUSSION Although cases of malignant melanoma originating from the skin are generally noted, cases of malignant melanoma originating from the lung are rare. In the present case, a left pneumonectomy was performed for an undiagnosed hilar tumour, which was subsequently pathologically diagnosed as hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin. Cases of spontaneous regression of primary malignant melanomas with regional metastasis have previously been reported [3]. Therefore, in the present case, we suspect that a malignant melanoma developed in the skin, metastasized to the lung and subsequently metastasized to the hilar lymph node; thereafter, the primary and the lung metastasis regressed spontaneously and only the hilar lymph node metastasis persisted. Although cases of primary pulmonary malignant melanoma are rare, some cases have been reported previously [4], indicating the possibility that the hilar tumour was a lymph node metastasis from a primary melanoma of the lung that had disappeared following spontaneous regression. However, in the present case, it is difficult to confirm the true primary tumour site. With regard to the treatment of metastatic malignant melanomas, previous studies have indicated that surgical resection of pulmonary metastases could improve patient outcomes [5]. Hence, our standard treatment for pulmonary metastasis from malignant melanoma is surgical resection, according to Thomford’s criteria. Moreover, primary melanoma of the lung can also be treated by surgical resection, and several reports have described long-term patient survival in such cases [4]. In the present case, we performed radical pneumonectomy because of hilar involvement. Wedge resection is the most common type of pulmonary resection for metastatic melanoma [5]. However, lung lobectomy or pneumonectomy should also be considered an alternative procedure for pulmonary metastatic melanoma because
regional lymph node involvement of the lung containing the pulmonary metastasis is frequently observed in cases of melanoma. Amelanotic malignant melanomas mimic benign and malignant variants of both melanocytic and non-melanocytic lesions [1, 2]. Metastatic lesions could be amelanotic even in cases where the primary tumour was pigmented [2]. In this present case, we diagnosed the patient with amelanotic malignant melanoma based on the characteristic histological and immunohistological findings such as prominent eosinophilic nucleoli and positive results on staining for MART-1. Moreover, the treatment of amelanotic tumours is similar to the treatment of its pigmented counterpart [1]. In conclusion, in cases where an undiagnosed tumour of the lung is detected, a malignant melanoma should be considered in the differential diagnosis, and, if possible, surgical resection should be performed. Moreover, the possibility of spontaneous regression of the primary lesion and the amelanotic subtype of malignant melanomas should be considered in such cases in clinical practice. Conflict of interest: none declared.
REFERENCES [1] Giuliano AE, Cochran AJ, Morton DL. Melanoma from unknown primary site and amelanotic melanoma. Semin Oncol 1982;9:442–7. [2] Koch SE, Lange JR. Amelanotic melanoma: the great masquerader. J Am Acad Dermatol 2000;42:731–4. [3] Smith JL Jr, Stehlin JS Jr. Spontaneous regression of primary malignant melanomas with regional metastases. Cancer 1965;18:1399–415. [4] Taboada CF, McMurray JD, Jordan RA, Seybold WD. Primary melanoma of the lung. Chest 1972;62:629–31. [5] Petersen RP, Hanish SI, Haney JC, Miller CC III, Burfeind WR Jr, Tyler DS et al. Improved survival with pulmonary metastasectomy: an analysis of 1720 patients with pulmonary metastatic melanoma. J Thorac Cardiovasc Surg 2007;133:104–10.
European Journal of Cardio-Thoracic Surgery 46 (2014) 919–920 doi:10.1093/ejcts/ezu105 Advance Access publication 17 March 2014
Hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin Kentaro Miura, Takashi Eguchi*, Gaku Saito and Kazuo Yoshida Division of Thoracic Surgery, Shinshu University, Matsumoto, Japan * Corresponding author. Division of Thoracic Surgery, Shinshu University, 3-1-1 Asahi, Matsumoto 390-8621, Japan. Tel: +81-263-372657; fax: +81-263-372721; e-mail: [email protected] (T. Eguchi). Received 16 December 2013; received in revised form 7 February 2014; accepted 18 February 2014
Abstract We report a case of hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin. A left pulmonary nodule was detected during a check-up in a 58-year old woman. Chest computed tomography indicated a large left hilar mass located between the upper and lower lobes. She underwent left pneumonectomy with mediastinal lymph node dissection, and the tumour was diagnosed as hilar lymph node metastasis of an amelanotic malignant melanoma; however, the primary lesion could not be detected. Thus, the possibility of spontaneous regression of the primary lesion and the amelanotic subtype of malignant melanomas should be considered in clinical practice.
INTRODUCTION Malignant melanoma is a cancer with a high associated mortality rate. Malignant melanomas generally originate from the skin and commonly metastasize to the lung. Although melanoma can also originate from the lung, such cases are extremely rare. Amelanotic malignant melanoma is a rare subtype of malignant melanoma, where little or no pigmentation is noted on visual inspection. Amelanotic malignant melanoma reportedly accounts for 1.8–8.1% of all cases of malignant melanomas [1, 2]. In the present report, we describe a case of hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin, for which left pneumonectomy was performed.
CASE A left pulmonary nodule was detected on chest computed tomography (CT) in a 58-year old woman during a check-up. She did not have any history of major disease or any specific cancer-related familial history. Chest radiography indicated the presence of a large mass shadow in the left hilum. Chest CT further indicated a large hilar mass, 42 × 34 × 50 mm in size, between the left upper and lower lung lobes (Fig. 1). The left upper and lower bronchi and interlobar pulmonary artery were adjacent to and displaced by the tumour. 18F-fluorodeoxyglucose–positron emission tomography (FDG–PET) performed 1 month after tumour detection showed high FDG accumulation in the tumour. The maximum standardized uptake value was found to be 9.3, and no abnormal accumulation at any other site. Based on the findings of transbronchoscopic lung aspiration cytology, the tumour was diagnosed as malignant; however, it was difficult to histologically diagnose the tumour based on the aspiration cytology findings.
The patient’s lung function parameters were as follows: forced vital capacity, 3050 ml and 120% of the predicted value; forced expiratory volume in 1 s, 2350 ml; percentage of predicted carbon monoxide diffusion lung capacity, 104%. No definitive preoperative diagnosis was established; however, we decided to perform radical resection of the left hilar tumour as CT and FDG–PET showed no signs of involvement at other sites and the patient had adequate lung function. During surgery, a large mass was detected between the interlobar pulmonary artery and the left upper and lower bronchi. Hence, we determined that radical surgery could not be achieved because of inadequate margins if we were to preserve either the left upper lobe or the left lower lobe. Thus, left pneumonectomy with systematic mediastinal lymph node dissection was performed according to the standard node dissection for lung cancer surgery (ND2a-1). Intrathoracic left superior and inferior pulmonary vein dissection was difficult because of compression by the bulky hilar tumour and, therefore, these vessels were dissected and divided intrapericardially. A subsequent pathological examination indicated the presence of a non-pigmented white tumour consisting of proliferating epithelioid and spindle cells, with a large round nucleus containing prominent eosinophilic nucleoli (Fig. 2A and B). Moreover, certain lymph node components were also detected around the tumour tissue on histological examination. No nodular lesions were noted in the left lung parenchyma. No metastasis to the mediastinal lymph nodes was diagnosed. On immunohistochemical staining, the tumour cells yielded positive results for MART-1 and S100, but negative results for HMB45 (Fig. 2C). Thus, the tumour was eventually diagnosed as hilar lymph node metastasis of an amelanotic malignant melanoma of unknown origin. The primary lesion could not be detected by postoperative systemic examinations. The patient’s postoperative course was uneventful, and she has been followed up for 2 years without any evidence of recurrence.
© The Author 2014. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
CASE REPORT
Keywords: Amelanotic malignant melanoma • Lymph node metastasis • Pneumonectomy
920
K. Miura et al. / European Journal of Cardio-Thoracic Surgery
Figure 1: Chest computed tomography images (A, axial section; B, sagittal section) showing a large hilar mass located between the left upper and lower lung lobes.
Figure 2: (A) Section of the left lung indicating a non-pigmented white tumour. (B) Analysis of the tumours under high magnification (haematoxylin and eosin staining; original magnification ×500) showing proliferating epithelioid cells with a large round nucleus containing prominent eosinophilic nucleoli. (C) Immunohistochemical staining showing that the tumour cells were positive for MART-1.
DISCUSSION Although cases of malignant melanoma originating from the skin are generally noted, cases of malignant melanoma originating from the lung are rare. In the present case, a left pneumonectomy was performed for an undiagnosed hilar tumour, which was subsequently pathologically diagnosed as hilar lymph node metastasis of amelanotic malignant melanoma of unknown origin. Cases of spontaneous regression of primary malignant melanomas with regional metastasis have previously been reported [3]. Therefore, in the present case, we suspect that a malignant melanoma developed in the skin, metastasized to the lung and subsequently metastasized to the hilar lymph node; thereafter, the primary and the lung metastasis regressed spontaneously and only the hilar lymph node metastasis persisted. Although cases of primary pulmonary malignant melanoma are rare, some cases have been reported previously [4], indicating the possibility that the hilar tumour was a lymph node metastasis from a primary melanoma of the lung that had disappeared following spontaneous regression. However, in the present case, it is difficult to confirm the true primary tumour site. With regard to the treatment of metastatic malignant melanomas, previous studies have indicated that surgical resection of pulmonary metastases could improve patient outcomes [5]. Hence, our standard treatment for pulmonary metastasis from malignant melanoma is surgical resection, according to Thomford’s criteria. Moreover, primary melanoma of the lung can also be treated by surgical resection, and several reports have described long-term patient survival in such cases [4]. In the present case, we performed radical pneumonectomy because of hilar involvement. Wedge resection is the most common type of pulmonary resection for metastatic melanoma [5]. However, lung lobectomy or pneumonectomy should also be considered an alternative procedure for pulmonary metastatic melanoma because
regional lymph node involvement of the lung containing the pulmonary metastasis is frequently observed in cases of melanoma. Amelanotic malignant melanomas mimic benign and malignant variants of both melanocytic and non-melanocytic lesions [1, 2]. Metastatic lesions could be amelanotic even in cases where the primary tumour was pigmented [2]. In this present case, we diagnosed the patient with amelanotic malignant melanoma based on the characteristic histological and immunohistological findings such as prominent eosinophilic nucleoli and positive results on staining for MART-1. Moreover, the treatment of amelanotic tumours is similar to the treatment of its pigmented counterpart [1]. In conclusion, in cases where an undiagnosed tumour of the lung is detected, a malignant melanoma should be considered in the differential diagnosis, and, if possible, surgical resection should be performed. Moreover, the possibility of spontaneous regression of the primary lesion and the amelanotic subtype of malignant melanomas should be considered in such cases in clinical practice. Conflict of interest: none declared.
REFERENCES [1] Giuliano AE, Cochran AJ, Morton DL. Melanoma from unknown primary site and amelanotic melanoma. Semin Oncol 1982;9:442–7. [2] Koch SE, Lange JR. Amelanotic melanoma: the great masquerader. J Am Acad Dermatol 2000;42:731–4. [3] Smith JL Jr, Stehlin JS Jr. Spontaneous regression of primary malignant melanomas with regional metastases. Cancer 1965;18:1399–415. [4] Taboada CF, McMurray JD, Jordan RA, Seybold WD. Primary melanoma of the lung. Chest 1972;62:629–31. [5] Petersen RP, Hanish SI, Haney JC, Miller CC III, Burfeind WR Jr, Tyler DS et al. Improved survival with pulmonary metastasectomy: an analysis of 1720 patients with pulmonary metastatic melanoma. J Thorac Cardiovasc Surg 2007;133:104–10.
