Mucinous adenocarcinomas of the thymus: report of 2 cases and review of the literature

Primary mucinous adenocarcinoma of the anterior mediastinum with HER-2 mutation: A rare case report

We report the case of a 68-year-old male whose Computed Tomography (CT) scan presented a mass (68*62*54 mm) of the right anterior mediastinal and pathologically diagnosis was mucinous adenocarcinoma(MA). The peripheral vessels are surrounded by the big mass in the anterior mediastinum which was associated with multiple metastases, thus we performed palliative chemoradiotherapy and we tried Human Epidermal Growth Factor Receptor-2 (HER-2) inhibitors based on the Next Generation Sequencing. The patient passed away 16 months after the onset of the disease. In this report, we review the rare case of anterior mediastinum MA as well as perspectives for potential future treatments.

A case report of anterior mediastinal signet ring cell carcinoma

RATIONALE

Anterior mediastinal signet ring cell carcinoma (SRCC) is a rare tumor that has only been reported in two cases of thymic cancer. Positive immunohistochemistry (IHC) staining for caudal-type homeobox (CDX) 2, cytokeratin (CK) 20 and special AT-rich binding protein (SATB) 2 usually indicate gastrointestinal tumors but begin to appear in thymic cancers with enteric differentiation. Here, we describe a case of the anterior mediastinal SRCC with enteric differentiation who was correctly treated with surgery and chemo-radiation and was alive after four months.

PATIENT CONCERNS

A 48-year-old female presented without chest and lung symptoms had an anterior mediastinal mass during a routine physical examination. Laboratory examinations showed an elevated level of serum carbohydrate antigen (CA)-125 at 73.63 U/mL. Chest computed tomography (CT) showed an irregular soft tissue density shadow with heterogeneous enhancement in the anterior mediastinum. The tumor had invaded the pericardium, the left septal nerve and the innominate and was completely removed after anterior mediastinal surgery. Postoperative pathological examinations revealed signet ring cell features and positive staining for CDX2, CK20, SATB2 and Ki-67 (Li: 70%). The samples were negative for cluster of differentiation (CD)-5, CK7, thyroid transcription factor (TTF) 1, NapsinA, CerbB-2, P53 and PD-L1 by IHC examinations. The suspected diagnosis was an anterior mediastinal SRCC that had originated in the digestive system.

DIAGNOSIS

The patient was diagnosed with anterior mediastinal SRCC.

INTERVENTIONS

The patient was treated with surgery and combined chemo-radiotherapy.

OUTCOMES

The patient had no recurrence or metastasis after five months.

LESSONS

We describe a rare case of the anterior mediastinal SRCC of unknown origin. Our case, for the first time shows that surgery combined with chemo-radiotherapy is an effective treatment regimen for anterior mediastinal SRCC.

Thymic Carcinoma: A Review

The diagnosis of thymic carcinoma may pose significant problems not necessarily in the histopathological diagnosis but rather in assigning the thymus as specific origin. Often the tissue available for interpretation is obtained via a mediastinocopic biopsy, which raises two different issues -minimal tissue and lack of specific features to make a carcinoma of thymic origin. In addition, if to that conundrum we add that there is no magic immunohistochemical stain that will unequivocally lead to the interpretation of thymic carcinoma, then we are left with a true clinical-radiological-pathological correlation. In this review, we will highlight some of those challenges that diagnostic surgical pathologists may encounter in the histopathological assessment of thymic carcinoma as well as in the staging of these tumors.

Primary mucinous adenocarcinoma of the thymus: A case report

Primary thymic mucinous adenocarcinoma is extremely rare; to our knowledge, only 16 cases have been reported to date. A 68-year-old man presented to a previous hospital due to massive pericardial effusion. Cytological examination of the pericardial effusion revealed the presence of adenocarcinoma, and computed tomography showed an anterior mediastinal mass lesion invading the pericardium. Because systemic examination failed to detect other lesions, except for liver metastasis, mediastinal lymph node swelling, and pleural dissemination, a thoracoscopic biopsy of the mediastinal and pleural tumor was performed. The pathological diagnosis was thymic mucinous adenocarcinoma. Although he received chemotherapy, he died due to cancer 6 months after the biopsy.

Primary mucinous adenocarcinoma of the thymus; a rare type of thymic carcinoma. Case Report

Mucinous adenocarcinoma of the thymus is a particularly rare type among thymic carcinomas. Here, we report a patient who underwent complete surgical resection of the primary mucinous adenocarcinoma of the thymus. She was 74 years old and presented with a 60-mm multilocular cystic tumor in her right anterior mediastinum. We performed extended thymo-thymectomy with partial resection of the right upper lobe and pathologically diagnosed the patient with Masaoka stage II mucinous adenocarcinoma of the thymus. Immunohistochemistry showed the absence of PD-L1, suggesting that immune check point inhibitors targeting PD-1/PD-L1 might not be effective in this case. The increased preoperative serum levels of CA19-9 decreased after the operation. CA19-9 is a biomarker for disease status. Future reports should help elucidate the pathogenesis of this disease.

Primary thymic adenocarcinoma with an aggressive clinical course: An autopsy case showing signet ring cell-like features

Thymic adenocarcinoma is an extremely rare neoplasm, and little is known about its pathogenesis and clinical characteristics. A 52‐year‐old man presented to our clinic with severe dyspnea. At initial presentation, massive carcinomatous pleuritis and pericarditis were observed, and a lobulated mass in the anterior mediastinum was found on computed tomography. Cytological examination revealed adenocarcinoma accompanied by signet ring cells; however, his tumor showed aggressive growth without any possibility of treatment, and he died as a result of cancer progression within one month of admission. An autopsy confirmed thymic adenocarcinoma showing various histological features including mucinous, signet ring cell‐like, and trabecular features. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) (AE1/AE3) but negative for TTF‐1. In addition, some tumor cells were positive for CD5 and KIT. Further examination revealed that tumor cells of the nonmucinous type were positive for CK7, and negative for CK20 and caudal‐type homeobox 2 (CDX2). The tumor cells with mucinous and signet ring‐like features were positive for CK20 and CDX2 and negative for CK7, indicating enteric differentiation. In particular, tumor cells with signet ring cell‐like features indicated widespread lymphangitic carcinomatosis and pulmonary tumor thrombotic microangiopathy (PTTM). The presence of signet ring cell‐like features with enteric differentiation is suggestive of a fulminant clinical course due to widespread lymphangiosis carcinomatosa and PTTM in patients with thymic adenocarcinoma.

Key points

Thymic adenocarcinoma is an extremely rare neoplasm.

Histological features of thymic adenocarcinoma include mucinous, signet ring cell‐like, and trabecular features.

Tumor cells with signet ring cell‐like features indicate widespread lymphangitic carcinomatosis and pulmonary tumor thrombotic microangiopathy.

The presence of signet ring cell‐like features with enteric differentiation is associated with a fulminant clinical course.

Primary Thymic Signet Ring Cell Adenocarcinoma: A Currently Unrecognized Variant

We describe the first case of primary thymic adenocarcinoma with signet ring cell features. The patient was a 39-year-old Filipino male who presented with a huge anterior mediastinal mass extending to the left supraclavicular fossa, which underwent an incisional biopsy. Extensive clinicoradiological work-up showed no evidence of any primary tumor in other organs, and radiological imaging confirmed a primary tumor location in the thymic area. He later developed bilateral pleural and pericardial effusions and eventually died of his tumor. The biopsy contained a neoplastic growth of solid nests made of cells with prominent signet ring features in sclerotic stroma. Immunohistochemically, the tumor cells were reactive for cytokeratin 7, carcinoembryonic antigen, and CD5 and negative for cytokeratin 20, TTF1, napsin A, α-fetoprotein, PAX-8, CD-117, CA19-9, CA-125, CDX2, p63, and CD99. No genetic alterations of ALK, RET, and ROS1 were found, nor was any ALK or ROS1 immunostaining detected, as known to occur in a fraction of primary pulmonary adenocarcinomas. Morphologically, this thymic tumor resembled signet ring cell adenocarcinomas of other locations, including, stomach, pancreas, and lung, but CD5 immunoreactivity strongly supported the clinical and radiological evidence of a primary thymic origin. In the English literature, only 58 cases of primary thymic adenocarcinoma are on record and this is the first report of a signet ring cell variant, which further broadens the morphological spectrum of thymic adenocarcinoma subtypes.

Characterization of genetic aberrations in a single case of metastatic thymic adenocarcinoma

BACKGROUND

Thymic adenocarcinoma is an extremely rare subtype of thymic epithelial tumors. Due to its rarity, there is currently no sequencing approach for thymic adenocarcinoma.

METHODS

We performed whole exome and transcriptome sequencing on a case of thymic adenocarcinoma and performed subsequent validation using Sanger sequencing.

RESULTS

The case of thymic adenocarcinoma showed aggressive behaviors with systemic bone metastases. We identified a high incidence of genetic aberrations, which included somatic mutations in RNASEL, PEG10, TNFSF15, TP53, TGFB2, and FAT1. Copy number analysis revealed a complex chromosomal rearrangement of chromosome 8, which resulted in gene fusion between MCM4 and SNTB1 and dramatic amplification of MYC and NDRG1. Focal deletion was detected at human leukocyte antigen (HLA) class II alleles, which was previously observed in thymic epithelial tumors. We further investigated fusion transcripts using RNA-seq data and found an intergenic splicing event between the CTBS and GNG5 transcript. Finally, enrichment analysis using all the variants represented the immune system dysfunction in thymic adenocarcinoma.

CONCLUSION

Thymic adenocarcinoma shows highly malignant characteristics with alterations in several cancer-related genes.

Histologic characteristics of thymic adenocarcinomas: Clinicopathologic study of a nine-case series and a review of the literature

Primary thymic adenocarcinoma is an extraordinarily rare malignancy; only 49 cases have been reported in the medical literature to date. Because of its rarity, clinical and pathologic characteristics of thymic adenocarcinoma are unclear. We present nine cases of primary thymic adenocarcinoma and discuss clinicopathologic findings in the context of the existing literature. Two-hundred twenty-six thymic carcinoma cases were diagnosed at Samsung Medical Center in Korea, from January, 2001 to July, 2016. Nine of these 226 cases were primary thymic adenocarcinomas. The mean age of primary thymic adenocarcinoma patients was 53.6 years, slightly younger than the mean age of patients with thymic squamous cell carcinomas. The male to female ratio was 2:1. Symptoms, if present, were usually due to compression by the tumor. Tumors showed an extra- or intra-cellular mucin and tubular growth pattern, with CK20- and CDX2-immunoreactivity, similar to adenocarcinomas of the lower intestinal tract. Twenty-five previously reported cases, classified as mucinous adenocarcinoma and adenocarcinoma, not otherwise specified, also had similar characteristics to enteric-type adenocarcinoma and generally expressed CK20, CDX2, CEA, and/or MUC2. Some of these cases had a thymic cyst. These characteristics are different from those of papillary thymic carcinomas, which are morphologically similar to papillary thyroid carcinomas, express CK7 but not CK20, and are often associated with thymoma. The prognosis of thymic adenocarcinoma, enteric type appeared to be worse than the prognosis of papillary thymic carcinoma or carcinoma with adenoid cystic carcinoma-like features. In summary, we demonstrated that common primary thymic adenocarcinomas show enteric-type differentiation with mucin. This tumor type has distinct clinical, pathological, immunohistochemical and prognostic characteristics and is different from other subtypes of thymic adenocarcinoma, papillary thymic carcinoma, and carcinoma with adenoid cystic carcinoma-like features.

A Rare Case of Primary Tubular Adenocarcinoma of the Thymus, Enteric Immunophenotype: A Case Study and Review of the Literature

Thymic carcinomas are uncommon malignant tumors, and thymic adenocarcinomas are extremely rare. Here, we describe a case of primary thymic adenocarcinoma in a 59-year-old woman. Histological examination of the tumor revealed tubular morphology with expression of cytokeratin 20 and caudal-type homeobox 2 according to immunohistochemistry, suggesting enteric features. Extensive clinical and radiological studies excluded the possibility of an extrathymic primary tumor. A review of the literature revealed only two global cases of primary tubular adenocarcinomas of the thymus with enteric immunophenotype.

Adenocarcinoma of the thymus, enteric type: report of 2 cases, and proposal for a novel subtype of thymic carcinoma

We report 2 cases of primary thymic adenocarcinoma with enteric differentiation. One carcinoma occurred in a 41-year-old man as a 7-cm-diameter cystic tumor and the other one in a 39-year-old woman as a 6-cm-diameter solid mass. Both tumors were located in the anterior mediastinum. Clinical staging did not reveal any extrathymic tumor. Histologically, the tumors were classified as adenocarcinoma, not otherwise specified, and a mucinous (colloid) carcinoma, respectively. Immunohistochemically, both tumors were positive for cytokeratin 20 (CK20), CDX2, and carcinoembryonic antigen, reflecting enteric differentiation. A review of the literature on 43 other cases of primary thymic adenocarcinomas suggested 11 further cases with enteric differentiation, as assessed by CK20 and/or CDX2 expression. We propose that thymic adenocarcinoma with enteric differentiation represents a novel subtype of thymic carcinoma. It is mostly of mucinous morphology and frequently associated with thymic cysts. The clinical outcome is variable. Recognition of primary thymic adenocarcinoma with enteric differentiation is helpful for the differentiation from metastatic disease, mainly from the gastrointestinal tract.

Immunohistochemistry in the diagnosis of thymic epithelial neoplasms

The diagnosis of thymic epithelial neoplasms is normally rendered after careful evaluation of their histologic features. In some cases, however, the morphological heterogeneity or overlap with neoplasms of other organ systems can lead to diagnostic uncertainty. On the basis of this, the use of immunohistochemical stains as a diagnostic adjunct has become a popular tool. Although undoubtedly, immunohistochemistry has its role in the diagnosis of difficult cases, to date there are no specific markers that would distinguish thymic epithelial neoplasms from other tumors and interpretation of immunohistochemical results should only ever be made in conjunction with accurate morphologic analysis and careful clinical evaluation. This article will review the current knowledge of the immunohistochemical phenotype of thymic epithelial neoplasms with particular emphasis on its use for diagnostic purposes and the latest advances in this field.

Primary adenocarcinoma of the thymus: an immunohistochemical and molecular study with review of the literature

Background

Primary adenocarcinoma of thymus is extremely rare.

Case presentation

This is a case of primary adenocarcinoma with intestinal differentiation and focal mucin production in the thymus. Thymic cyst was associated with this tumor. Intestinal differentiation was confirmed by immunohistochemical stain with positivity for CDX-2, CK20, villin, MOC31 and focal positivity of CK7. Array comperative genomic hybridization (CGH) analysis showed a complex pattern of chromosomal imbalances including homozygous deletion at the HLA locus in chromosomal region 6p21.32.

Conclusion

This rare tumor shows a similar genetic aberration with other studied thymic epithelial tumors.

Primary thymic mucinous adenocarcinoma: a case report

Primary thymic mucinous adenocarcinoma is an extremely rare aggressive subtype of thymic carcinoma. With a review of literatures, only nine cases have been reported up to present. A 36-year-old woman was admitted for further evaluation and treatment of a mediastinal mass. The patient had no medical history of cancer. The clinicoradiological examination disclosed no tumor elsewhere. After the surgical excision of mediastinal mass, it was grossly a round semi-solid mass with mucin-filled cystic areas. Microscopically solid areas showed cords, small nests and dilated glands infiltrating the fibrotic parenchyma, while the cystic areas were lined by mucinous epithelium with tumor cells floating in extracellular-mucin pools. Some cystic walls underwent malignant transformation of the benign thymic epithelium. Immunohistochemically, the tumor cells were positive for cytokeratin (CK) 7, CK20, CD5, and CDX-2, and negative for thyroid transcription factor-1. In conclusion, the mucinous thymic adenocarcinoma should be recognized as a separate histopathological entity and considered in the differential diagnosis of mediastinal carcinomas.

Adenocarcinoma arising in an ectopic mediastinal pancreas

Pancreatic ectopia in the mediastinum is rare, and there are no reports that it has ever given rise to malignancy. Here we report a case of adenocarcinoma arising in ectopic pancreatic tissue in the mediastinum of a 66-year-old woman. The tumor arose in a partially cystic and partially solid ectopic pancreas containing both exocrine and endocrine components. Thorough clinical examination and clinical follow-up did not reveal other primary sites. The tumor was partially resected but metastasized to the anterior sternum 6 months later and was re-excised. No other similar cases of primary mediastinal pancreatic adenocarcinoma are on record in medical literature.

Thymic adenocarcinoma with sarcomatoid features characterized by intracaval tumor growth: report of a case

Primary thymic adenocarcinoma is an extremely rare tumor. This report describes a case of thymic adenocarcinoma with a peculiar pathological feature and clinical course. A 54-year-old man complained of cough, dyspnea, and chest pain. Computed tomography scans revealed an anterior mediastinal mass with intracaval growth into the superior vena cava. No definitive diagnosis could be made after several examinations and palliative radiotherapy was performed. He passed away 56 days after the appearance of the initial symptoms. An autopsy revealed that the mediastinal tumor obstructed not only the superior vena cava but also the pulmonary arteries. The histological findings revealed the tumor to be an adenocarcinoma with sarcomatous features. The tumor was immunohistochemically positive for CD5 and negative for thyroid transcription factor-1. These results suggested the tumor to be a thymic adenocarcinoma with sarcomatoid features; furthermore, the tumor invaded the great vessels, thus resulting in a poor prognosis.

Giant-cell anaplastic carcinoma with osteoclastic giant cells of the chest cavity: a distinctive form of thymic carcinoma?

Here, the authors describe a case of giant-cell anaplastic carcinoma with osteoclastic giant cells of the chest cavity-which could be a distinctive form of thymic carcinoma-which expressed CD5 and CD45. To the authors' knowledge, there has been no previous report on this subject. A 62-year-old woman presented with continuous pain in the left back associated with coughing and shortness of breath for more than 2 months prior to referral to the hospital. Palliative resection of a mediastinal tumor was performed. During the operation, it was found that the mass occupied most of the chest invading the chest wall, aorta, vena cava, and lung tissue. The patient soon died from diabetic complications in spite of anti-infection treatment. The tumor was composed of large areas of necrosis and anaplastic neoplastic giant cells with high mitotic activity, and osteoclast-like cells; there was marked inflammatory cell infiltration. The anaplastic neoplastic giant cells were immunoreactive for CKpan, CD5, CD45, VIM, and p53. Approximately 50% to 60% of the tumor cells showed immunoreactivity for Ki-67. In situ hybridization for Epstein-Barr virus-encoded RNA was negative for tumor cells and nonneoplastic osteoclastic giant cells. Because this tumor is very rare, extensive clinical, radiological, and morphological examinations as well as immunohistochemical studies are essential to make the diagnosis.

Mucinous adenocarcinoma of the thymus: a case report

A mucinous adenocarcinoma of the thymus is rare, and there is presently limited information on the clinical aspects of this uncommon type of tumor. Only six cases have been reported in the literature. A 49-year-old Japanese male presented with an anterior mediastinal mass, and underwent a tumor resection. Histologically the tumor consisted of a mucinous adenocarcinoma with pleural dissemination. Postoperative radiotherapy and chemotherapy were performed. The patient is still alive with pleural dissemination 11 months after surgery.

Mucinous adenocarcinoma of the thymus: a distinct variant of thymic carcinoma

BACKGROUND

Primary thymic mucinous adenocarcinoma is a recently described subtype of thymic carcinoma, which behaves aggressively.

METHODS

The authors analyzed the clinical and pathological findings of three cases of thymic mucinous adenocarcinoma, and reviewed five cases previously reported in the English literature.

RESULTS

The patients were two males and one female between the ages of 38 and 55 years. Macroscopically, the tumors were mostly solid and white to yellowish-white. Areas with a gelatinous appearance were present. Histologically, all of the tumors were adenocarcinomas with abundant mucin production, which resembled the mucinous adenocarcinomas of other organs. Malignant tumor cells in nests, tubules and cribriform structures floated in pools of extracellular mucin. In one case, associated thymic cysts were found at the periphery of the tumor. The cyst wall was partially lined by malignant mucinous epithelium, which showed transition from benign thymic epithelium. Immunohistochemically, all of the tumors showed positive immunoreactivity for cytokeratin (CK) 20 and carcinoembryonic antigen (CEA). CD5 was diffusely positive in one case, and focally positive in the other two cases. The prognoses of these cases were extremely poor, and two of the patients died within 24 months.

CONCLUSION

Growing evidence suggests that mucinous adenocarcinoma is a distinct morphological variant of primary thymic carcinoma. We believe that clinicians and surgical pathologists should include thymic mucinous adenocarcinoma in the differential diagnosis of mediastinal adenocarcinoma.