A 27-year-old man was transferred to our hospital with the complaint of facial edema and diagnosis of giant anterior mediastinal tumor. But soon after admission, the size of the tumor decreased remarkably, although he had no particular treatment. As the tumor was not completely regressed, surgical resection was performed subsequently, and examination of the specimen showed small foci of seminoma within the area of dense fibrous scar tissue, originated from the thymus. While regression of germ cell tumors are well recognized in cases of nonseminomatous germ cell tumors, this phenomenon of primary mediastinal seminoma was not reported previously

Hamada Tetsuo

Joji Shirabe

Mori Yoshiaki

Takasaki Hidemi

Tanaka Koichi

Uchida Yuzo

Yokoyama Shigeo

Nagasaki University's Academic Output SITE: NAOSITE

Acta Med. Nagasaki 34: 28-31Spontaneous regression of mediastinal seminomaKoichi TANAKA *, Tetsuo HADAMA, Hidemi TAKASAKI,     Yoshiaki MoRI, Yuzo UCHIDA, Joji SHIRABE            and Shigeo YOKOYAMA **  * The Second Department of Surgery, ** Division of Pathology, Laboratory Center,     Oita Medical College, Oita, JapanReceived for publication, December 26, 1988ABSTRACT : A 27-year-old man was transferred to our hospital with the com-plaint of facial edema and diagnosis of giant anterior mediastinal tumor. But soon after admission, the size of the tumor decreased remarkably, although he had no particular treatment. As the tumor was not completely regressed, surgical resection was performed subsequently, and examination of the specimen showed small foci of seminoma within the area of dense fibrous scar tissue, originated from the thymus. While regression of germ cell tumors are well recognized in cases of non-seminomatous germ cell tumors, this phenomenon of primary mediastinal seminoma was not reported previously.       INTRODUCTION  There have been numerous reports in the literature of spontaneous regression of germ cell tumors. But, majority of the cases were non-seminomatous tumors, and spontaneous regression of seminoma was rare. Moreover, we could not find any other report of such phenomenon in mediastinal seminoma. There-fore, we report here our case of spontaneous regression of primary mediastinal semirioma.        CASE REPORT  The patient, 27-year-old man, was well until February 10, 19 8 8, when he noticed facial edema. He was admitted to the Beppu National Hospital two weeks later, because of being pointed out anterior mediastinal giant mass on chest roentgenogram and CT scan .(Fig. 1), and SVC syndrome on venography. There, heunderwent percutaneous needle aspiration biopsy, but the results yielded only to be suggestive of malignant tumor. Then, he was transferred to our hospital for further examina-tion on March 7. However, soon after the admission, facial edema diminished incidiously in spite of no particular treatment, and find-ings on physical examination became almost normal. Bilateral descended testes were normal to palpation. Medical and family histories were unremarkable.  Laboratory findings included a serum lactic dehydrogenase level of 6221U/L., total protein of 8.4g/1, 7-globulin rate of 33.8%, and BSR of 138mm. Tumor markers including CEA, a-fetoprotein, human chorionic gonadotropin, CA19-9, and SCC level were in normal range.  Chest roentgenogram on March 15 showed a remarkable decrease in size of the mediastinal mass. Similarly, chest CT scan revealed small solid mass in mediastinum but no pleural effusion (Fig.2).Fig. 1. Chest roentgenogram and CT scan show-       ed giant mass shadow in anterior media-       stinum. However, the tumor size was unchanged thereafter, and a surgical operation was subse-quently performed on April 4. Midsternal thoracotomy was performed. The solid tumor was in continuity with the thymus, and adhered closely to the superior vena cava and bilateral brachiocephalic veins. Nevertheless, the tumor was successfully removed together with the thymus and the superior vena cava, followed by reconstruction using two pieces of expanded-polytetrafluoroethylene artificial graft.  Pathologic Findings  Gross findings : The resected tumor was firm in consistency, measuring 93 X 70 X 28mm. The cut surface was well demarcated without a fibrous capsule, and had a whitish-yellow homogeneous appearance with some necrotic foci (Fig. 3).  Histological findings : Although most . area of the tumor was replaced by extensive fibrousFig. 2. Chest roentgenogram and CT scan show-       ed a remarkable decrease in size of the        mediastinal mass.tissue and some necrotic foci with lymphocytic infiltration and epithelioid granulomas (Fig. 4), clusters of large undifferentiated tumor cells with glycogen-rich pale cytoplasm were observ-ed only in small parts. These clusters were surrounded by lymphoid tissues which contained a few Hassall's corpuscles and granulomatous reaction (Fig. 5).  On the basis of these findings, this mediasti-nal tumor was diagnosed as a pure type of seminoma arising from the thymus.  Postoperatively, the patient was put on a regimen of Cisplatin, Vincristine, and Pepleo-mycine, followed by radiotherapy in a dose of 40Gy. He was doing well without recurrence 6 months after surgery.         DISCUSSION  Spontaneous regression of tumors is well known, but it is a rare phenomenon. The crite-Fig. 3. Whitish-yellow homogeneous cut surface        with some necrotic foci.Fig. 4. Extensive fibrous tissue with small        necrotic foci. ria of spontaneous regression is not yet defined, however, Everson and Colel) 2) suggested that spontaneous regression may be defined as a complete or partial disappearance of a malig-nant tumor in the absence of treatment that ordinarily is considered capable of producing regression. The regression needs not be progressed to complete disappearance of theFig. 5. Small foci of seminoma with a Hassal's        corpuscle (arrow). tumor. Patients with luekemia, lymphoma, and squamous cell carcinoma of the skin were excluded, because many patients with these lesions vary greatly in their rates of growth. According to this definition, they searched 176 cases of spontaneous regression from world medical literatures from 1900 to 1964, and thereafter, Uchino 3) also searched 83 cases from 1973 to 1982. And they showed that it was most frequent in adenocarcinoma of the kidney, neuroblastoma, malignant melanoma, and choriocarcinoma.  In relation to germ cell tumors, there have been some reports of spontaneous regression in the literature 4-6). However, the majority of these cases have involved non-seminomatous germ cell tumor of testis, most commonly choriocarcinoma and malignant teratoma 5 ). And case reports of spontaneous regression of pure semonoma has been rarer) 6) 8) _ Moreover, there have been no other previous reports of spontaneous regression of mediastinal seminoma except our case.  The actual mechanism of spontaneous regre-ssion of a tumor is obscure. But, postulated mechanisms generally include immunologic factors, hormonal factors, trauma (e. g., bio-psy, incomplete resection ), infection, drugs, or elimination of carcinogens. These mecha-nisms were discussed in detail elsewhere 2),7),10) In the case presented here, transcutaneous need-le biopsy, which could stimulate hormonal or immunological regulation, might be the most causative mechanism because neither anticancer drugs nor immunopotentiators were used.  Histologically, most area of the tumor ofthis case consisted with dence fibrous tissues, and only a small part revealed seminomatous appearance. This finding might not suppose to be a result of ischemic change due to vascular occulusion.  Spontaneous regression of malignant tumor is truely an existent phenomenon. Then, investigation of this mysterious phenomenon could give a clue to the resolving biological mechanisms and clinical therapy of cancer.           REFERENCES 1) EvI:IL90N,T.C., CoLE,W.H. : Spontaneous re-   gression of cancer. A study and abstract of    reports in the world medical literature and   personal communications concerning spon-   taneous regression of malignant disease.    Saunders, Philadelphia, 1966. 2) SMITHERS,D.W. : Spontaneous regression of    tumors. Clinical Radiology, 13: 132-137. 3) J.UCI-IINO,H.NAITO,Y.UNE, et al. : Spontaneous    regression of cancer. The Hokkaido Journal    of Medical Science, 59 (6) : 674-678,1984. 4) WAL,H.V., ARKENBOUT,P., BERGE,E.T. et al.    The therapeutic approach to intrathoratic    metastases of non-seminomatous testicular  tumor. Acta Chirurgica Belgica, 84 (6) : 349-  356, 1984. 5) FRANKLIN, C.I.V. : Spontanous regresson of    metastases from testicular tumors. A report    of six cases from one center. Clinical Radio-  logy, 28 (5) : 499-502, 1977. 6) HOLMES,A.S., KLIMBERG,I.W., STONESIFER,K.J.    et al. : Spontanous regression of testicular    seminoma : Case report. The Journal of   Urology, 135 (4) : 795-796, 1986. 7) COLE,W.H. : Relationship of causative factors    in spoutaneous regression of cancer to    immunologic factors possibly effective in    cancer. Journal of Surgical Oncology, 8 (5) :  391-411, 1976. 8) AzzoPARDI,J.G., HOFFBRAND,A.V. : Retrogres-   sion of testicular seminoma with viable   metastases. Journal of Clinical Pathology,   18 :135-141, 1965. 9) WEGENKE,J.D., CHUPREVICI-I,T.W., NILSSON,T.E.    G. : Retroperitoneal seminoma. The Journal   of Urology, 117 :262-263, 1977. 10) WEAVER, G.R., COHN, J.H., MINTZER, R.A.    Transient spontaneous regression of an   anterior mediastinal mass. Chest, 87 (4) : 547-  548, 1985.

Spontaneous regression of mediastinal seminoma

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Spontaneous regression of mediastinal seminoma

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