|Ahead of print publication
A case of soft-tissue tumor over the sternum: A rare case report
Sagar Dilip Rathod, Dhirendra Wagh, S Niveditha
Department of General Surgery, Datta Meghe Institute of Medical Sciences, Wardha, Maharashtra, India
|Date of Submission||21-May-2020|
|Date of Decision||16-Jul-2020|
|Date of Acceptance||14-Oct-2020|
|Date of Web Publication||03-Nov-2021|
Sagar Dilip Rathod,
Department of General Surgery, Datta Meghe Institute of Medical Sciences, Sawangi, Wardha - 442 001, Maharashtra
Source of Support: None, Conflict of Interest: None
The objective is to report a rare case of extragonadal seminoma over the manubrium sterni on the chest wall. A 42-year-old male patient, a chronic alcoholic for 10 years presented with a firm mass of approximate size 10 cm × 12 cm overlying the manubrium part of the sternum. A clinical diagnosis of soft-tissue tumor was made. All relevant preoperative workup was done. Fine-needle aspiration cytology of the mass was suggestive of serous cystic lesion with chronic inflammation. Wide local excision of the mass and primary closure of the wound was done, followed by histopathological examination. Unanticipatedly, on histology, the mass turned out to be extragonadal seminoma. Postoperative wound healing was satisfactory. Subsequently, the patient underwent adjuvant chemotherapy. Primary extragonadal seminoma itself is a rare tumor that affects mainly young people with mediastinum as the most commonly involved site and has higher chances of metastasis. This case of extragonadal seminoma (extragonadal germ cell tumour) over manubrium sterni without any mediastinal involvement in a patient in early forties presenting as soft-tissue tumor, itself is a rarer entity and perhaps one of the kinds. Hence, the case needs to be reported and further progression and prevention have to be discussed.
Keywords: Extragonadal tumor, sternum, seminoma
| > Introduction|| |
Germ cell tumors (GCTs) of the ovaries and testicles are common, but those occurring in extragonadal sites are relatively rare. This accounts for about 1% to 5% of all GCTs. The morphological classification of GCTs includes mature teratoma, immature teratoma, seminoma, yolk sac tumor, embryonal carcinoma, choriocarcinoma, and mixed GCT. Although the biology of extragonadal germ cell tumors (EGGCTs), especially that of primary mediastinal nonseminomatous GCT, is quite different, but their histological morphology is very similar to GCTs which are derived from primary gonadal sites.
The distinctive feature of extragonadal germ cell tumor is its involvement of the midline structures which can be located anywhere from the pineal gland to the coccyx. The favored sites are mediastinum, retroperitoneum, and brain followed by the sacrococcygeal region and pineal gland. However, cases of mandibular and facial EGGCTs have also been reported, but rare. Among the extragonadal germ cell tumors (EGCTs), the primary anterior mediastinal GCTs are the most common ones and these tumors originate in the anterior mediastinum without primary involvement of the gonads.
Here, we report a rarer and perhaps the first case of EGGCT over manubrium sterni.
| > Case Report|| |
A 40-year-old male with no known comorbidities presented to the surgery outpatient department with complaints of a large, slow growing, nontender mass over the upper aspect of the sternum of 2 years' duration. There was neither any history of trauma to the chest nor any history of respiratory complaints. On clinical evaluation, the respiratory parameters were within normal limits. The swelling was present over the manubrium part of the sternum, vertically extending for about 12 cm from the sternal notch to just above the level of nipple and horizontally extending for about 10 cm from the right midclavicular line to the left midclavicular line [Figure 1]a and [Figure 1]b. The mass was nontender and fixed to the sternum. Overlying skin appeared stretched without any pressure necrosis. The surface was uniformly smooth except over the left upper lateral portion of the swelling which was irregular and hard. The rest of the systemic examination and external genitalia were within normal limits.
|Figure 1: (a) Case picture anterior aspect. (b) Case picture lateral aspect|
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All relevant investigations were performed. The radiogram of the chest done was s/o hazy opacity in the right upper mediastinum [Figure 2]. On further evaluation with an HRCT of the thorax showed a lytic expansile lesion in the manubrium and upper body of the sternum which caused erosion and destruction of the anterior and posterior cortex of the sternum with contagious extension into adjacent soft tissue. Fine-needle aspiration cytology (FNAC) showed occasional leukocytes of polymorphs, lymphocytes, rare macrophages, sparse red blood cells, and granular thin material; few places show fragments of these cells with degenerated material; suggestive of the serous cystic lesion with chronic inflammation with no malignant cells seen (preoperatively FNAC could not diagnose seminoma). Ultrasonography (USG) of Inguino-Scrotal region revealed normal anatomy of testis and thereby gonadal primary tumor was ruled out. A normal USG of the abdomen and pelvis ruled out metastasis.
|Figure 2: Preoperative X-ray showing hazy opacity in the right upper mediastinum|
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With the clinical diagnosis of soft-tissue tumor over the sternum, the patient was planned for wide local excision of the lump. Intraoperatively, approximately 10 cm linear incision was taken over the swelling in the midline extending from 4 cm above the sternal notch. The mass was dissected and freed from the base and adjacent tissues. It was found to be firmly adherent to the sternum at its center, and hence a small chip of sternal bone was removed while dissection [Figure 3]. The mass was removed in toto. The primary closure of the wound was done.
|Figure 3: Intraoperative picture, anterior chest wall cleared of all the remnant seminoma tissue|
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Grossly, the specimen measured 13 cm × 12 cm × 6 cm. On the cut section, the lobulated whitish homogenous area was identified [Figure 4] and [Figure 5]. The specimen was sent for histopathological study. Histology showed large neoplastic cells with abundant clear cytoplasm, round nucleus and prominent nucleolus arranged in lobules which are separated by fibrous septa which contain lymphocytes. The histopathological features were suggestive of seminoma (Extragonadal GCT) [Figure 6].
|Figure 6: Histopathology image from the postoperative specimen; demonstrates large cells with clear cytoplasm, distinct borders, squared-off nuclei, and prominent nucleoli. Mix of lymphocytes seen|
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This is the largest and the only reported case of extragonadal seminoma till date from our institute and the only documented case of extragonadal seminoma over the sternum without mediastinal involvement till date.
Postoperative recovery was uneventful and the scar is healthy. The patient also underwent adjuvant chemotherapy with EP (Etoposide–Cisplatin) regimen, which he tolerated well.
| > Discussion|| |
Gonads are the most common site for germ cell tumors but it can be seen less often at other sites such as the pineal gland, sacrum, retroperitoneum, and mediastinum. Extragonadal origin germ cell tumors comprise 2%–5% of total GCTs. Out of all the primary mediastinal germ cell tumors, one-fifth of cases are primary mediastinal seminoma, anterior part of mediastinum being its usual location.
The origin of EGCTs sill is a mystery. The cytogenetic findings on chromosome 12q appear to suggest that extragonadal tumors could be of gonadal origin., The unusual placement of germ cells during embryo formation is a speculation of GCTs appearing at such unusual locations.
Mediastinal GCTs are morphologically and histologically similar to their gonadal counterparts but their different biologic behavior can be attributed to their development at a particular location other than gonads. Histopathologically, GCTs are classified into teratomas (including mature and immature groups), germinomas (seminomas), embryonal carcinoma, choriocarcinoma, yolk sac tumors, and mixed GCTs. These same variants can present at extragonadal sites and in malignant EGGCTs the most common histological variant is yolk sac tumor occurring most commonly in association with a teratoma and rarely occurs alone.
Around 30% of mediastinal seminoma are asymptomatic and are accidental finding on routinely done chest radiogram. Slowly growing extragonadal germ cell tumors produce few symptoms such as chest pain, dyspnea, and cough.
According to the results from an international analysis of 635 cases with extragonadal germ cell tumors, 83% (524) were nonseminomatous and 16% (104) were seminomatous germ cell tumors.,
We considered a differential diagnosis of soft-tissue tumor, primary large B-cell lymphoma, thymoma, and teratoma. The preoperative FNAC report was not correlating with the specimen histopathology. FNAC suggesting serous cystic lesion with chronic inflammation and no malignant cells was contradictory to the postoperative histopathological extragonadal germ cell tumor (seminoma) report. Certain features that are commonly associated with seminoma such as epithelioid granuloma, cystic changes, and lymphocytic infiltration, were not prominent in the histopathological examination, but immunohistochemistry was suggestive of cytoplasmic staining with placental-like alkaline phosphatase. Immunohistochemical studies for placental-like alkaline phosphatase might be of discriminatory value in similar cases.
Routine biopsy or orchidectomy is not indicated if no evidence of testicular abnormality or noninvolvement of retroperitoneal structures exists., Five-year survival rate for extragonadal seminoma is close to 90% whereas that of nonseminoma, which has a fairly poorer prognosis is 45%.,
The case was discussed in tumor board and advised adjuvant chemotherapy with the EP regimen (Etoposide-Cisplatin) × 4 cycles, 21 days apart. The serum tumor markers before chemotherapy is as follows: Serum Beta-human chorionic gonadotrophin (βhCG) <2.0 IU/L, serum alpha-fetoprotein (AFP) 4.5 ng/mL, and serum lactic dehydrogenase (LDH) 753 IU/L [Figure 7].
|Figure 7: Indiana University approach for patients with suprasternal GCT. AFP = Alpha-fetoprotein, BEP = Bleomycin, etoposide and cisplatin, hCG = Human chorionic gonadotropin, PMNSGCT = Primary mediastinal nonseminomastous germ cell tumors, TM = tumor markers, VIP = Etoposide, ifosfamide and cisplatin|
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The patient was followed up every 21 days for the subsequent chemotherapy cycle. He tolerated the chemotherapy well and on completion of four cycles of chemotherapy with EP regimen, tumor marker values were serum LDH 461 IU/L (753 IU/L before starting chemotherapy), serum βhCG 2.1 IU/L, and serum AFP 3.4 ng/mL (4.5 ng/mL before starting chemotherapy). On subsequent visits after 6 months, the patient had no evidence of recurrence [Figure 8].
| > Conclusion|| |
The thymus is many a times associated with mediastinal seminoma. According to old theories, origin of GCTs is extragonadal, due to the presence of germ cells (biphasic in nature) within the embryogenic thymus or germinal tumors may arise from the thymic gland during its embryogenesis due to maldevelopment. In recent studies, the suggestion has been made that all healthy persons have germ cells present at different ectopic sites, which during embryogenesis are distributed widely, functions by regulating somatic site function or distributing genetic information. As seems in my case, the old theory of tumor-associated with thymus does not apply here. Hence, the older theories are not applicable here and the recent theory on the presence of germ cells at different ectopic sites is acceptable.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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