Surg Today DOI 10.1007/s00595-014-0998-x
Case Report
Primary malignant melanoma of the thymus: report of a case Tetsuo Taniguchi · Koji Kawaguchi · Takayuki Fukui · Masashi Nishimura · Kohei Yokoi
Received: 27 January 2014 / Accepted: 10 June 2014 © Springer Japan 2014
Abstract A 61-year-old male was admitted to our hospital complaining of bloody sputum. A chest roentgenogram revealed a clearly demarcated mass located in the anterior mediastinum. Positron emission tomography revealed abnormal accumulation of 18F-fluorodeoxy glucose only in the anterior mediastinal tumor. A computed tomographyguided needle aspiration biopsy was performed, and the tumor was diagnosed as a malignant melanoma. Although the skin, eyeballs, oral cavity, nasal cavity, etc., were closely evaluated, no other lesion of malignant melanoma was detected except the mediastinal tumor. Hence, this tumor was diagnosed as a primary malignant melanoma. We performed total thymectomy, including the tumor, and combined resection of the adhesive bilateral lungs, pericardium and left brachiocephalic vein. Because the tumor was histologically surrounded by thymus tissue, we diagnosed it as a primary mediastinal malignant melanoma that originated in the thymus. Although the patient’s postoperative course was uneventful, he complained of back pain 5 months after the operation. Multiple bone metastases were found, and he received chemotherapy and radiotherapy, and is currently alive with disease 14 months after the primary treatment. Keywords Malignant melanoma · Mediastinum · Positron emission tomography T. Taniguchi (*) · K. Kawaguchi · T. Fukui · K. Yokoi Department of Thoracic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai‑cho, Showa‑ku, Nagoya 466‑8550, Japan e-mail: [email protected]‑u.ac.jp M. Nishimura Department of Thoracic Surgery, Tosei General Hospital, Seto, Japan
Introduction Malignant melanoma is a malignancy of melanocytes, which originates from the neural crest formed on the neural tube, and usually occurs in the skin. Therefore, it is difficult to imagine a primary malignant melanoma originating in the anterior mediastinum, where melanocytes do not usually exist. This report describes a case of malignant melanoma in the anterior mediastinum which is considered to have originated in the thymus.
Case report A 61-year-old male was referred to Nagoya University Hospital complaining of bloody sputum. At the time of admission, the patient had no other symptoms, and the results of clinical examinations and routine laboratory tests were within the normal limits. He had no history of other diseases and no specific history of an enlarging or changing nevus. A chest roentgenogram revealed a clearly demarcated mass measuring 15 cm in diameter located in the anterior mediastinum. Enhanced computed tomography (CT) of the chest showed a heterogeneous mass with an irregular margin in the anterior mediastinum and contact with the pericardium and bilateral lungs (Fig. 1a). A CT-guided needle aspiration biopsy was performed, and the mass was pathologically suspected to be a malignant melanoma. Positron emission tomography (PET) revealed an abnormal accumulation of 18F-fluorodeoxy glucose [maximum standardized uptake value (SUVmax); 6.7] in the mediastinal tumor, but no accumulation elsewhere (Fig. 1b). Although the skin, eyeballs, oral cavity, nasal cavity, esophagus, anorectal region, etc., were closely evaluated, no other lesions of malignant melanoma were
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Surg Today
Bilateral thoracotomy was performed through a clamshell incision to obtain a good exposure of the whole mediastinum and the bilateral thoracic cavities so that a complete resection of the tumor could be successfully carried out. A large solid tumor, which size was a child’s head, was found to be firmly adhered to the bilateral lungs, pericardium and left brachiocephalic vein. No pleural effusion or pleural dissemination was recognized. Total thymectomy with the tumor, and combined resection of the adhesive bilateral lungs, pericardium and left brachiocephalic vein, were performed. The patient’s postoperative course was uneventful. The macroscopic findings of the resected specimen revealed that the cut surface was black in color (Fig. 1c) and there was a solid encapsulated tumor measuring 14 × 13 × 8 cm, almost all of which was histologically surrounded by thymic tissue. The microscopic examination demonstrated that the tumor was composed of a diffuse proliferation of various sized atypical cells with eosinophilic cytoplasm and prominent nucleoli, not including the epithelial component. Some of these atypical cells contained bile-colored, fine and coarse cytoplasmic granules (Fig. 2a). Immunohistochemical staining indicated that these tumor cells were positively stained with the monoclonal antibody HMB-45 (Fig. 2b) and S-100. The negative surgical margins were microscopically confirmed, and the tumor was diagnosed to have no invasion to the resected neighboring organs, except the right upper lobe of the lung. Based on these findings, we diagnosed the tumor as a primary mediastinal malignant melanoma that originated in the thymus. Although the patient was well doing without adjuvant therapy, he complained of back pain 5 months after the operation. Multiple bone metastases were found by CT and PET, and he received chemotherapy and radiotherapy. He is currently alive with the disease 14 months after the primary treatment.
Discussion
Fig. 1 Contrast-enhanced chest computed tomography (a) showed a heterogeneous mass with an irregular margin in the anterior mediastinum, and contact with the pericardium and bilateral lungs. Positron emission tomography (b) revealed an abnormal accumulation of 18 F-fluorodeoxy glucose in the mass. The macroscopic findings of the resected specimen (c). The tumor had a multilobular appearance with hemorrhage
detected. Therefore, the tumor was diagnosed to be malignant melanoma of the anterior mediastinum, and primary surgical intervention was performed.
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Malignant melanoma results from the uncontrolled growth of pigment cells called melanocytes. Although most common in the skin, it can also occur in mucosal sites, such as the oral cavity, paranasal sinuses, esophagus, larynx, vagina and the anorectal region [1]. Primary malignant melanoma of the anterior mediastinal region is extremely rare, with fewer than 10 cases having been reported so far [2, 3]. Among them, three cases were reported as primary thymic malignant melanomas [4]. There are several clinical criteria that have to be established before making a diagnosis of primary melanoma of the lung: (1) no previously removed skin tumor; (2) no excised ocular tumor; (3) a solitary tumor in the
Surg Today
an occurrence of malignant transformation from a teratoma to melanoma. In the field of gynecology and obstetrics, the malignant transformation of a cystic teratoma has been reported to occur in about 1.8 % of cases [7]. Of course, we cannot strictly rule out that the tumor in the present case was a metastatic melanoma to the anterior mediastinum. However, no cutaneous, ocular, anal, rectal, nasal or oral mucosal lesions were demonstrated on a thorough physical examination. Furthermore, no abnormalities except the mediastinal tumor were detected by PET. Based on these findings, we diagnosed that the tumor was a primary thymic malignant melanoma. The prognostic factors for non-cutaneous malignant melanomas have not been clearly identified due to lack of data from a sufficient number of cases. In the reports of primary malignant melanoma of the mediastinum in adults [3], the prognosis was unfavorable. There is currently no consensus regarding the approach to adjuvant therapy. Surgical excision with adequate margins is the primary treatment modality for cutaneous melanoma [8], and this recommendation may also be appropriate for non-cutaneous malignant melanomas. Further accumulation of knowledge and experience is needed to formulate the optimal therapy for non-cutaneous malignant melanoma. Conflict of interest The authors have no conflicts of interest to disclose in association with this study.
Fig. 2 The microscopic findings of the tumor (hematoxylin-eosin stain, original magnification ×400) (a). Immunohistochemical staining for HMB-45 (b) was positive in the tumor cells (original magnification ×400)
surgical specimen and (4) no demonstrable melanoma in other organs at the time of surgery [1]. The histogenesis of the malignant melanoma of the anterior mediastinum is enigmatic. Parker and colleagues reported a case of benign nevus cell aggregates in the thymus [5]. Nevus cell aggregates in lymph nodes are also known to be a rare but possible source of melanoma [2]. Regarding phenomenonspecific malignant melanoma, Das Gupta and colleagues demonstrated that primary skin melanomas occasionally regress spontaneously, and the only clinical manifestation in affected patients is the presence of metastatic melanoma in the regional lymphatic basin or in the viscera [6]. Although such a metastatic melanoma of unknown primary origin is one of the most interesting presentations, it rarely occurs. Another possible explanation of the origin is that there was
References 1. Wilson RW, Moran CA. Primary melanoma of the lung: a clinicopathologic and immunohistochemical study of eight cases. Am J Surg Pathol. 1997;21:196–202. 2. Vlodavsky E, Ben-Izhak O, Best LA, Kerner H. Primary malignant melanoma of the anterior mediastinum in a child. Am J Surg Pathol. 2000;24:747–9. 3. Karuppiah SV, Buchan KG. Primary malignant melanoma: a rare cause of mediastinal mass. Jpn J Thorac Cardiovasc Surg. 2006;54:396–8. 4. Shimizu J, Kawaura Y, Tatsuzawa Y, Kinoshita T, Nozaki Z, Ohta Y, et al. Malignant melanoma originating in the thymus. Aust NZJ Surg. 2000;70:753–5. 5. Parker JR, Ro JY, Ordonez NG. Benign nevus cell aggregates in the thymus: a case report. Mod Pathol. 1999;12:329–32. 6. Das Gupta TK, Brasfield RD, Paglia MA. Primary melanoma in unusual sites. Surg Gynecol Obstet. 1969;128:841–8. 7. Moehrle M, Fischbach H, Nuessle B, Rassner G. Primary malignant melanoma arising in a cystic necrotic ovarian teratoma. Eur J Obstet Gynecol Reprod Biol. 2001;99:268–71. 8. Bichakjian CK, Halpern AC, Johnson TM, Foote Hood A, Grichnik JM, Swetter SM, et al. Guidelines of care for the management of primary cutaneous melanoma. J Am Acad Dermatol. 2011;65:1032–47.
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Case Report
Primary malignant melanoma of the thymus: report of a case Tetsuo Taniguchi · Koji Kawaguchi · Takayuki Fukui · Masashi Nishimura · Kohei Yokoi
Received: 27 January 2014 / Accepted: 10 June 2014 © Springer Japan 2014
Abstract A 61-year-old male was admitted to our hospital complaining of bloody sputum. A chest roentgenogram revealed a clearly demarcated mass located in the anterior mediastinum. Positron emission tomography revealed abnormal accumulation of 18F-fluorodeoxy glucose only in the anterior mediastinal tumor. A computed tomographyguided needle aspiration biopsy was performed, and the tumor was diagnosed as a malignant melanoma. Although the skin, eyeballs, oral cavity, nasal cavity, etc., were closely evaluated, no other lesion of malignant melanoma was detected except the mediastinal tumor. Hence, this tumor was diagnosed as a primary malignant melanoma. We performed total thymectomy, including the tumor, and combined resection of the adhesive bilateral lungs, pericardium and left brachiocephalic vein. Because the tumor was histologically surrounded by thymus tissue, we diagnosed it as a primary mediastinal malignant melanoma that originated in the thymus. Although the patient’s postoperative course was uneventful, he complained of back pain 5 months after the operation. Multiple bone metastases were found, and he received chemotherapy and radiotherapy, and is currently alive with disease 14 months after the primary treatment. Keywords Malignant melanoma · Mediastinum · Positron emission tomography T. Taniguchi (*) · K. Kawaguchi · T. Fukui · K. Yokoi Department of Thoracic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumai‑cho, Showa‑ku, Nagoya 466‑8550, Japan e-mail: [email protected]‑u.ac.jp M. Nishimura Department of Thoracic Surgery, Tosei General Hospital, Seto, Japan
Introduction Malignant melanoma is a malignancy of melanocytes, which originates from the neural crest formed on the neural tube, and usually occurs in the skin. Therefore, it is difficult to imagine a primary malignant melanoma originating in the anterior mediastinum, where melanocytes do not usually exist. This report describes a case of malignant melanoma in the anterior mediastinum which is considered to have originated in the thymus.
Case report A 61-year-old male was referred to Nagoya University Hospital complaining of bloody sputum. At the time of admission, the patient had no other symptoms, and the results of clinical examinations and routine laboratory tests were within the normal limits. He had no history of other diseases and no specific history of an enlarging or changing nevus. A chest roentgenogram revealed a clearly demarcated mass measuring 15 cm in diameter located in the anterior mediastinum. Enhanced computed tomography (CT) of the chest showed a heterogeneous mass with an irregular margin in the anterior mediastinum and contact with the pericardium and bilateral lungs (Fig. 1a). A CT-guided needle aspiration biopsy was performed, and the mass was pathologically suspected to be a malignant melanoma. Positron emission tomography (PET) revealed an abnormal accumulation of 18F-fluorodeoxy glucose [maximum standardized uptake value (SUVmax); 6.7] in the mediastinal tumor, but no accumulation elsewhere (Fig. 1b). Although the skin, eyeballs, oral cavity, nasal cavity, esophagus, anorectal region, etc., were closely evaluated, no other lesions of malignant melanoma were
13
Surg Today
Bilateral thoracotomy was performed through a clamshell incision to obtain a good exposure of the whole mediastinum and the bilateral thoracic cavities so that a complete resection of the tumor could be successfully carried out. A large solid tumor, which size was a child’s head, was found to be firmly adhered to the bilateral lungs, pericardium and left brachiocephalic vein. No pleural effusion or pleural dissemination was recognized. Total thymectomy with the tumor, and combined resection of the adhesive bilateral lungs, pericardium and left brachiocephalic vein, were performed. The patient’s postoperative course was uneventful. The macroscopic findings of the resected specimen revealed that the cut surface was black in color (Fig. 1c) and there was a solid encapsulated tumor measuring 14 × 13 × 8 cm, almost all of which was histologically surrounded by thymic tissue. The microscopic examination demonstrated that the tumor was composed of a diffuse proliferation of various sized atypical cells with eosinophilic cytoplasm and prominent nucleoli, not including the epithelial component. Some of these atypical cells contained bile-colored, fine and coarse cytoplasmic granules (Fig. 2a). Immunohistochemical staining indicated that these tumor cells were positively stained with the monoclonal antibody HMB-45 (Fig. 2b) and S-100. The negative surgical margins were microscopically confirmed, and the tumor was diagnosed to have no invasion to the resected neighboring organs, except the right upper lobe of the lung. Based on these findings, we diagnosed the tumor as a primary mediastinal malignant melanoma that originated in the thymus. Although the patient was well doing without adjuvant therapy, he complained of back pain 5 months after the operation. Multiple bone metastases were found by CT and PET, and he received chemotherapy and radiotherapy. He is currently alive with the disease 14 months after the primary treatment.
Discussion
Fig. 1 Contrast-enhanced chest computed tomography (a) showed a heterogeneous mass with an irregular margin in the anterior mediastinum, and contact with the pericardium and bilateral lungs. Positron emission tomography (b) revealed an abnormal accumulation of 18 F-fluorodeoxy glucose in the mass. The macroscopic findings of the resected specimen (c). The tumor had a multilobular appearance with hemorrhage
detected. Therefore, the tumor was diagnosed to be malignant melanoma of the anterior mediastinum, and primary surgical intervention was performed.
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Malignant melanoma results from the uncontrolled growth of pigment cells called melanocytes. Although most common in the skin, it can also occur in mucosal sites, such as the oral cavity, paranasal sinuses, esophagus, larynx, vagina and the anorectal region [1]. Primary malignant melanoma of the anterior mediastinal region is extremely rare, with fewer than 10 cases having been reported so far [2, 3]. Among them, three cases were reported as primary thymic malignant melanomas [4]. There are several clinical criteria that have to be established before making a diagnosis of primary melanoma of the lung: (1) no previously removed skin tumor; (2) no excised ocular tumor; (3) a solitary tumor in the
Surg Today
an occurrence of malignant transformation from a teratoma to melanoma. In the field of gynecology and obstetrics, the malignant transformation of a cystic teratoma has been reported to occur in about 1.8 % of cases [7]. Of course, we cannot strictly rule out that the tumor in the present case was a metastatic melanoma to the anterior mediastinum. However, no cutaneous, ocular, anal, rectal, nasal or oral mucosal lesions were demonstrated on a thorough physical examination. Furthermore, no abnormalities except the mediastinal tumor were detected by PET. Based on these findings, we diagnosed that the tumor was a primary thymic malignant melanoma. The prognostic factors for non-cutaneous malignant melanomas have not been clearly identified due to lack of data from a sufficient number of cases. In the reports of primary malignant melanoma of the mediastinum in adults [3], the prognosis was unfavorable. There is currently no consensus regarding the approach to adjuvant therapy. Surgical excision with adequate margins is the primary treatment modality for cutaneous melanoma [8], and this recommendation may also be appropriate for non-cutaneous malignant melanomas. Further accumulation of knowledge and experience is needed to formulate the optimal therapy for non-cutaneous malignant melanoma. Conflict of interest The authors have no conflicts of interest to disclose in association with this study.
Fig. 2 The microscopic findings of the tumor (hematoxylin-eosin stain, original magnification ×400) (a). Immunohistochemical staining for HMB-45 (b) was positive in the tumor cells (original magnification ×400)
surgical specimen and (4) no demonstrable melanoma in other organs at the time of surgery [1]. The histogenesis of the malignant melanoma of the anterior mediastinum is enigmatic. Parker and colleagues reported a case of benign nevus cell aggregates in the thymus [5]. Nevus cell aggregates in lymph nodes are also known to be a rare but possible source of melanoma [2]. Regarding phenomenonspecific malignant melanoma, Das Gupta and colleagues demonstrated that primary skin melanomas occasionally regress spontaneously, and the only clinical manifestation in affected patients is the presence of metastatic melanoma in the regional lymphatic basin or in the viscera [6]. Although such a metastatic melanoma of unknown primary origin is one of the most interesting presentations, it rarely occurs. Another possible explanation of the origin is that there was
References 1. Wilson RW, Moran CA. Primary melanoma of the lung: a clinicopathologic and immunohistochemical study of eight cases. Am J Surg Pathol. 1997;21:196–202. 2. Vlodavsky E, Ben-Izhak O, Best LA, Kerner H. Primary malignant melanoma of the anterior mediastinum in a child. Am J Surg Pathol. 2000;24:747–9. 3. Karuppiah SV, Buchan KG. Primary malignant melanoma: a rare cause of mediastinal mass. Jpn J Thorac Cardiovasc Surg. 2006;54:396–8. 4. Shimizu J, Kawaura Y, Tatsuzawa Y, Kinoshita T, Nozaki Z, Ohta Y, et al. Malignant melanoma originating in the thymus. Aust NZJ Surg. 2000;70:753–5. 5. Parker JR, Ro JY, Ordonez NG. Benign nevus cell aggregates in the thymus: a case report. Mod Pathol. 1999;12:329–32. 6. Das Gupta TK, Brasfield RD, Paglia MA. Primary melanoma in unusual sites. Surg Gynecol Obstet. 1969;128:841–8. 7. Moehrle M, Fischbach H, Nuessle B, Rassner G. Primary malignant melanoma arising in a cystic necrotic ovarian teratoma. Eur J Obstet Gynecol Reprod Biol. 2001;99:268–71. 8. Bichakjian CK, Halpern AC, Johnson TM, Foote Hood A, Grichnik JM, Swetter SM, et al. Guidelines of care for the management of primary cutaneous melanoma. J Am Acad Dermatol. 2011;65:1032–47.
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