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

Thymic Adenocarcinoma With Metastasis to the Left Orbit: A Case Report

We present the case of a 57-year-old female who initially presented with a chief complaint of left-sided orbital headaches and associated left eyelid swelling. Initial imaging work-up with CT head/orbit revealed soft tissue enhancement of the left orbital roof, concerning for neoplastic process (primary lymphoma versus extracranial primary tumor versus metastatic tumor). Further imaging studies with CT chest/abdomen/pelvis revealed an anterior mediastinal mass, concerning for possible thymoma versus lymphoma. The patient underwent further consultation with the Hematology/Oncology and Ophthalmology Departments, which recommended definitive biopsies from both sites, which showed matching histologic findings of moderately differentiated enteric-type adenocarcinoma with positive staining for CDX2, an intestinal marker. Thymic carcinomas are rare cancers that account for approximately 0.06% of all malignancies and require a high degree of clinical suspicion. Extrathoracic metastases from thymic carcinomas, especially to the orbit, is a rare occurrence and the exact incidence of this phenomenon is unknown. This case represents the diagnostic challenges associated with a rare cancer type and underscores the importance of a multidisciplinary approach to patient care.

Systemic chemotherapy for unresectable or recurrent primary thymic adenocarcinoma of enteric type

Primary thymic adenocarcinoma of enteric type is a very rare subtype of thymic carcinoma. Choosing appropriate systemic chemotherapy for patients with unresectable or recurrent disease remain a big challenge. We present a case of 38-year-old man with primary thymic adenocarcinoma of enteric type. The patient received multiline chemotherapy. Metastatic lesions were effectively controlled by FOLFOX (oxaliplatin/5-fluorouracil/leucovorin) chemotherapy. According to the present case and the literature review, FOLFOX and XELOX (capecitabine/oxaliplatin) regimens are reasonable treatment choice for unresectable or recurrent primary thymic adenocarcinoma of enteric type, even in the first-line chemotherapy.

Desmoplastic Adamantinoma-like Thymic Carcinoma: Clinicopathologic, Immunohistochemical, and Molecular Study of 5 Cases

Five cases of a heretofore unreported rare variant of thymic carcinoma characterized by a striking resemblance to adamantinoma of the mandible are described. The tumors occurred in 4 women and 1 man aged 58 to 76 years (mean: 67.8 y); they arose in the anterior mediastinum and measured from 5.3 to 12.0 cm in greatest diameter (mean: 8.9 cm). Presenting symptoms included chest pain, shortness of breath, and in 2 patients, pleural effusion. One tumor was asymptomatic and discovered incidentally. Histologically, the tumors were extensively desmoplastic, and the cellular proliferation was characterized by multiple islands of squamous epithelium with striking peripheral palisading of nuclei and central areas containing clear cells resembling a stellate reticulum. Areas of preexisting spindle cell thymoma were identified in 2 cases; these areas gradually merged with the higher-grade component of the lesion. Cystic changes were noted in 3 cases. Immunohistochemical studies in 3 cases showed the tumor cells were positive for cytokeratins, p40 and p63, and all showed a high proliferation rate (>50% nuclear positivity) with Ki-67. Next-generation sequencing was performed in 2 cases that showed amplification of the AKT1 gene (copy numbers 6 and 13). Clinical follow-up in 3 patients showed recurrence and metastasis after 1 and 2 years; 1 patient passed away 2 years after diagnosis due to the tumor. Desmoplastic adamantinoma-like thymic carcinoma represents an unusual histologic variant of thymic carcinoma that needs to be distinguished from metastases from similar tumors to the mediastinum.

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.

The 2021 WHO Classification of Tumors of the Thymus and Mediastinum: What Is New in Thymic Epithelial, Germ Cell, and Mesenchymal Tumors?

This overview of the fifth edition of the WHO classification of thymic epithelial tumors (including thymomas, thymic carcinomas, and thymic neuroendocrine tumors [NETs]), mediastinal germ cell tumors, and mesenchymal neoplasms aims to (1) list established and new tumor entities and subtypes and (2) focus on diagnostic, molecular, and conceptual advances since publication of the fourth edition in 2015. Diagnostic advances are best exemplified by the immunohistochemical characterization of adenocarcinomas and the recognition of genetic translocations in metaplastic thymomas, rare B2 and B3 thymomas, and hyalinizing clear cell carcinomas. Advancements at the molecular and tumor biological levels of utmost oncological relevance are the findings that thymomas and most thymic carcinomas lack currently targetable mutations, have an extraordinarily low tumor mutational burden, but typically have a programmed death-ligand 1^high phenotype. Finally, data underpinning a conceptual advance are illustrated for the future classification of thymic NETs that may fit into the classification scheme of extrathoracic NETs. Endowed with updated clinical information and state-of-the-art positron emission tomography and computed tomography images, the fifth edition of the WHO classification of thymic epithelial tumors, germ cell tumors, and mesenchymal neoplasms with its wealth of new diagnostic and molecular insights will be a valuable source for pathologists, radiologists, surgeons, and oncologists alike. Therapeutic perspectives and research challenges will be addressed as well.

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.

Thymic adenocarcinoma accompanied by type A thymoma and pulmonary minimally invasive adenocarcinoma and harboring distinct gene alterations: A case report

RATIONALE

Thymic adenocarcinoma is an extremely rare thymic carcinoma. The exact genetic alteration associated with thymic adenocarcinoma is unclear. Here, we report a case of thymic adenocarcinoma accompanied by type A thymoma and pulmonary minimally invasive adenocarcinoma (MIA).

PATIENT CONCERNS

A 53-year-old woman presented with multiple nodules in the mediastinum and lung. Thoracic computed tomography revealed nodules in the anterior superior mediastinum and anterior mediastinum near the right pericardium and ground-glass opacity (GGO) in the right superior lobe of the lung.

DIAGNOSIS

The tumor in the anterior superior mediastinum was diagnosed as primary thymic papillary adenocarcinoma. The tumor in the anterior mediastinum near the right pericardium was diagnosed as type A thymoma. The GGO of the right superior lobe of the lung was diagnosed as a MIA.

INTERVENTION

The patient underwent thoracoscopic mediastinal tumor resection and partial lobectomy in our hospital.

OUTCOMES

The postoperative course was uneventful. The patient is alive and free of the disease for 22 months after diagnosis.

LESSONS

Thyroid transcription factor 1 (TTF-1) was positive in this case of thymic adenocarcinoma, which indicated that a thymic adenocarcinoma with TTF-1-positive may not necessarily be a metastasis of lung or thyroid adenocarcinoma. The positive staining of CD5 and CD117 can help us to confirm the thymic origin. Molecular genetic analysis indicated that these tumors harbored different mutations. The thymic adenocarcinoma and type A thymoma both had the mutation of KMT2A, but the mutation sites were different. KMT2A mutation may be a common genetic change in thymic tumorigenesis. The genetic alterations disclosed in this study will help expand the understanding of thymic tumors.

Metastatic thymic-enteric adenocarcinoma responding to chemoradiation plus anti-angiogenic therapy: A case report

BACKGROUND

Thymic-enteric adenocarcinoma with positive expression of CDX2 and CK20 is rare in adults, with only 16 reported cases. However, standard treatment options for this type of thymic adenocarcinoma has not yet been established. Therefore, we report a case of stage IV thymic-enteric adenocarcinoma treated with radiotherapy, chemotherapy, and anti-angiogenesis therapy.

CASE SUMMARY

We report a case of thymic-enteric adenocarcinoma occurring in a 44-year-old woman. The tumor was considered unresectable owing to its invasiveness. The patient was treated with six cycles of oxaliplatin (130 mg/m², day 1) and capecitabine (1000 mg/m² BID, days 1-14). During the first three cycles of chemotherapy, concurrent radiotherapy (60 Gy/30 fractions) and anti-angiogenic therapy using apatinib were recommended. The primary tumor achieved partial remission based on the Response Evaluation Criteria in Solid Tumors. During follow-up, there was no evidence of disease relapse, except a high serum CA19-9 level. The patient is alive and regularly followed. Based on the previous literature and the present case, we believe that early diagnosis of thymic-enteric adenocarcinoma is important.

CONCLUSION

XELOX (capecitabine plus oxaliplatin) combined with radiotherapy is an optional therapy for inoperable thymic-enteric adenocarcinoma.

Common and rare carcinomas of the thymus

Thymic carcinoma encompasses a diverse group of rare tumors that occur almost exclusively in the prevascular (anterior) mediastinum. Thymic carcinomas have a worse outcome than thymomas with a median time to death of under 3 years. These tumors lack the typical lobulation of thymomas, exhibit commonly more cytologic atypia, are associated with a desmoplastic stromal reaction, and lack thymocytes, features that distinguish them from thymomas. The most common thymic carcinoma is squamous cell carcinoma; other subtypes include mucoepidermoid carcinoma, NUT carcinoma, and adenocarcinoma, among others. Largely due to multi-institutional and global efforts and meta-analysis of case reports and series, some of the thymic carcinoma subtypes have been studied in more detail and molecular studies have also been performed. Morphology and immunophenotype for the vast majority of thymic carcinoma subtypes are similar to their counterparts in other organs. Therefore, the distinction between thymic carcinoma and metastatic disease, which is relatively common in the prevascular mediastinum, can be challenging and in general requires clinical and radiologic correlation. Although surgical resection is the treatment of choice, only 46 to 68% of patients with thymic carcinoma can undergo resection as many other tumors present at high stage with infiltration into vital neighboring organs. These patients are usually treated with chemotherapy and/or radiation. The search for better biomarkers for prognosis and treatment of thymic carcinomas is important for improved management of these patients and possible targeted therapy.

Pathological and clinical features of enteric adenocarcinoma of the thymus. A pooled analysis of cases from a reference center and systematic review of the literature

BACKGROUND

Primary enteric adenocarcinoma of the thymus (EAT) is a recently proposed rare subtype of thymic carcinoma. Unlike thymic carcinomas with squamous histology, for which clinical guidelines are available, little knowledge is available regarding the clinical and pathological features of EAT, and there is no consensus on the best treatment algorithm for such tumors.

METHODS

We performed a systematic review of the literature, searching for all cases of EAT reported. We also retrospectively reviewed all cases of EAT treated at the European Institute of Oncology (IEO) between January 2000 and January 2020. Individual patient data were extracted and analyzed in order to delineate clinical and pathological features, as well as patients' prognosis and treatments outcome, evaluated in terms of Disease free Survival (DFS), Progression free survival (PFS) and overall survival (OS).

RESULTS

Thirty-three cases (29 reported in literature and 4 new cases treated at IEO) of thymic adenocarcinoma deploying enteric differentiation as defined by WHO-criteria were analyzed. All tumors showed positive immunoreactivity for cytokeratin (CK) 20 and/or caudal type homeobox 2 (CDX2). Data on molecular profiling by next-generation sequencing were available in only 3 cases, and did not show actionable findings. At diagnosis, 11 pts had an early-stage (Masaoka I-II) and 22 a locally advanced (10 pts) or metastatic (12 pts) disease. Median-DFS of patients with localized disease was 12 months (95% CI, 7-19). Patients who received systemic chemotherapy were mostly treated with regimens commonly used for thymic epithelial tumors, with a discouraging PFS of 3-5 months for patients with stage IV disease. Median OS of the whole population was 34 months (95% CI, 24-NA:. mOS was not reached for patients with stage I-II disease versus 34 months in stage III-IV (p < 0.05).

CONCLUSION

Available evidence suggests that EAT represents a distinct entity in the context of thymic epithelial tumors, characterized by aggressive clinical behavior, poor responsiveness to chemotherapy and dismal patients prognosis. More research is needed to better define optimal management strategies for patients with such rare disease.

Genomic alterations in thymoma-molecular pathogenesis?

Thymomas and thymic carcinomas (TCs) are neoplasms of thymic epithelial cells. Thymomas exhibit a low mutational burden and a few recurrently mutated genes. The most frequent missense mutation p.(Leu404His) affects the general transcription factor IIi (GTF2I) and is specific for thymic epithelial tumors (TETs). The clinically indolent types A and AB thymomas express the miRNA cluster C19MC. This miRNA cluster known to be the largest in the human genome, is-with expression otherwise restricted mostly to embryonal tissue-silenced in the more aggressive type B thymomas and TCs. Thymomas associated with the autoimmune disease myasthenia gravis (MG) exhibit more frequent gene copy number changes and an increased expression of proteins homologous to molecules that are targets for autoantibodies. TCs, however, display a higher mutational burden, with frequent mutations of TP53 and epigenetic regulatory genes and loss of CDKN2A. The knowledge of molecular alterations in TETs fosters the understanding of their pathogenesis and provides guidance for further studies that may lead to the development of targeted therapies.

Thymic enteric type adenocarcinoma: A case report with cytological features

Primary thymic adenocarcinoma is an extremely rare tumor, and thymic enteric type adenocarcinoma has recently been proposed as a distinct pathological entity. Herein, we report the first cytological description of thymic enteric type adenocarcinoma. A 29-year-old Japanese female without a significant past medical history was found to have an abnormal chest shadow. Chest computed tomography demonstrated a well-circumscribed tumor in the anterior mediastinum, and thymectomy was performed. The Papanicolaou staining of the touch smear of the resected tumor demonstrated tightly cohesive epithelial cell clusters in a necrotic background. These cells were cuboidal to columnar in shape and had large round to oval nuclei with conspicuous nucleoli. Some of these neoplastic cells had intracytoplasmic mucin. Immunocytochemically, the neoplastic cells were positive for cytokeratin 20 and CDX-2. Histopathological study revealed tubular and papillotubular neoplastic growth composed of cuboidal to columnar neoplastic cells that contained large round to oval nuclei. Some of the neoplastic cells had intracytoplasmic mucin. Immunohistochemical study confirmed the expression of cytokeratin 20 and CDX-2. The final diagnosis of thymic enteric type adenocarcinoma was made. The cytological and immunocytochemical features of this case led to a diagnosis of enteric type adenocarcinoma. However, these features alone cannot be differentiated from a metastatic adenocarcinoma arising from the gastrointestinal tract. Cytological examination of a fine-needle aspiration of the mediastinal tumor has been reported to be useful in making a diagnosis. Therefore, an awareness of this new pathological entity is important for differentiating a thymic tumor from a metastatic carcinoma in the thymus.

Cytologic Characteristics of Thymic Adenocarcinoma with Enteric Differentiation: A Study of Four Fine-Needle Aspiration Specimens

Thymic adenocarcinoma is extremely rare. Although its histologic features have been occasionally reported, a lack of description of the cytologic features has hampered the prompt and accurate diagnosis of this condition. Herein, we describe the cytologic findings and histology of four aspiration cytology specimens of thymic adenocarcinoma. The specimens were obtained from primary tumors, metastatic lymph nodes, and pericardial effusions. All four specimens showed three-dimensional glandular clusters with a loss of polarity and nuclear overlapping. One specimen had extensive extracellular mucinous material. Three specimens contained tumor cells with intracytoplasmic vacuoles. While the specimen with extracellular mucin showed relatively mild cytologic atypia, other specimens exhibited more atypical cytologic changes: irregular nuclear membranes, a coarse chromatin pattern, and prominent nucleoli. The cytologic features were correlated with the histologic features in each case of enteric type thymic adenocarcinoma. The differential diagnosis included other thymic carcinomas, yolk sac tumors, and metastatic adenocarcinoma from the lung or colorectum.

KRAS mutation-positive mucinous adenocarcinoma originating in the thymus

Thymic carcinoma is a rare, aggressive disease with a low 5-year survival rate. The most common histological neoplastic thymic tumor subtype is squamous cell. We describe an interesting case of a 39-year-old woman who presented with mucinous adenocarcinoma that originated in the thymus and was treated via radical resection and venoplasty of the superior vena cava (SVC). Macroscopically, the resected tumor contained a solid region and multiple cysts with abundant mucin. Microscopic examination showed a papillary growth pattern of goblet cells with round nuclei. Based on the histopathological and immunohistochemical findings and other inspections, the tumor was eventually diagnosed as a mucinous adenocarcinoma of the thymus. It was classified as Masaoka-Koga stage III owing to tumor invasion into the left brachiocephalic vein and pericardium. Polymerase chain reaction identified a Kirsten rat sarcoma viral oncogene homolog (KRAS) G12V mutation in the tumor. There were no mutations in the epidermal growth factor (EGFR) gene or a fusion gene of the echinoderm microtubule-associated protein-like 4 (EML4) and the anaplastic lymphoma kinase (ALK). A year later, multiple lung metastases were detected, and the patient underwent chemotherapy. She is alive 34 months after the initial surgery. This is the first report of a KRAS mutation-positive mucinous adenocarcinoma originating in the thymus. The treatment, diagnosis, and pathological findings of the patient are discussed.

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.

The 2015 World Health Organization Classification of Tumors of the Thymus: Continuity and Changes

This overview of the 4th edition of the World Health Organization (WHO) Classification of thymic tumors has two aims. First, to comprehensively list the established and new tumor entities and variants that are described in the new WHO Classification of thymic epithelial tumors, germ cell tumors, lymphomas, dendritic cell and myeloid neoplasms, and soft-tissue tumors of the thymus and mediastinum; second, to highlight major differences in the new WHO Classification that result from the progress that has been made since the 3rd edition in 2004 at immunohistochemical, genetic and conceptual levels. Refined diagnostic criteria for type A, AB, B1-B3 thymomas and thymic squamous cell carcinoma are given, and it is hoped that these criteria will improve the reproducibility of the classification and its clinical relevance. The clinical perspective of the classification has been strengthened by involving experts from radiology, thoracic surgery, and oncology; by incorporating state-of-the-art positron emission tomography/computed tomography images; and by depicting prototypic cytological specimens. This makes the thymus section of the new WHO Classification of Tumours of the Lung, Pleura, Thymus and Heart a valuable tool for pathologists, cytologists, and clinicians alike. The impact of the new WHO Classification on therapeutic decisions is exemplified in this overview for thymic epithelial tumors and mediastinal lymphomas, and future perspectives and challenges are discussed.

Successful multimodality treatment for locally advanced primary thymic adenocarcinoma: report of a case

Although the optimal treatment strategy for locally advanced thymic carcinomas has yet to be determined, complete resection of the tumor after induction chemoradiotherapy (CRT) can sometimes provide a good chance of being cured. A 61-year-old woman was diagnosed with locally advanced primary thymic carcinoma, which invaded bilateral brachiocephalic veins and superior vena cava with intraluminal tumor thrombus. Induction CRT was performed, and a partial response to the treatment was achieved. Subsequent radical surgery was successfully performed by the median full sternotomy with a right transmanubrial osteomuscular sparing approach (TMA). The patient is currently alive and has remained disease-free for a year. The TMA is useful for extensive surgery of locally advanced thymic carcinoma because it can provide good exposure of the operative field without post-operative functional limitation of upper limbs.

[Thymic carcinomas]

Thymic carcinomas (TC) are approximately 10 times less prevalent than thymomas but of high clinical relevance because they are more aggressive, less frequently resectable than thymomas and usually refractory to classical and targeted long-term treatment approaches. Furthermore, in children and adolescents TC are more frequent than thymomas and particularly in this age group, germ cell tumors need to be a differential diagnostic consideration. In diagnostic terms pathologists face two challenges: a), the distinction between thymic carcinomas and thymomas with a similar appearance and b), the distinction between TC and histologically similar metastases and tumor extensions from other primary tumors. Overcoming these diagnostic challenges is the focus of the new WHO classification of thymic epithelial tumors. The objectives of this review are to highlight novel aspects of the WHO classification of thymic carcinomas and to address therapeutically relevant diagnostic pitfalls.

Metastatic Thymic Adenocarcinoma from Colorectal Cancer

This report describes the case of a 57-year-old man with an anterior mediastinal tumor. Four years previously, he underwent laparoscopic anterior resection for sigmoid colon cancer. Thirty months after that procedure, bilateral pulmonary metastasectomy was performed. Twelve months later, follow-up computed tomography revealed a 1-cm pulmonary nodule on the upper lobe of the right lung and a solid mass on the anterior mediastinum, and the patient was also observed to have an elevated serum carcinoembryonic antigen (CEA) level. Repeated pulmonary nodule resection and total thymectomy were performed. Immunohistochemical staining of the anterior mediastinal tumor revealed adenocarcinoma, and his serum CEA level returned to normal after the operation. These findings strongly suggested metastatic thymic adenocarcinoma from a colorectal cancer.

Colon cancer chemotherapy for a patient with CDX2-expressing metastatic thymic adenocarcinoma: a case report and literature review

We report the case of a 59-year-old man with thymic adenocarcinoma who was treated with colon cancer chemotherapy. He was referred to our hospital for an anterior mediastinal mass and multiple bone metastases that were found by computed tomography. Needle biopsy of the mediastinal tumor revealed a caudal-type homeobox 2 (CDX2)-positive adenocarcinoma. Neither upper nor lower gastrointestinal endoscopic examinations revealed any evidence of a primary tumor. The patient was administered CapeOX (capecitabine and oxaliplatin) and FOLFIRI (fluorouracil, leucovorin and irinotecan)/cetuximab. He died 6 months after diagnosis. Primary thymic adenocarcinoma was confirmed by autopsy. As far as we know, this is the first report in which colon cancer chemotherapy was used to treat CDX2-positive metastatic thymic adenocarcinoma.

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.