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

Clinical characteristics and prognosis of primary thymic adenocarcinoma: A single-center retrospective analysis

BACKGROUND

Primary thymic adenocarcinoma (PTAC) is an extremely rare disease with a poor prognosis. In the present study, we sought to analyze the clinical characteristics and prognostic factors of patients with PTAC.

METHODS

A total of 14 patients with PTAC treated at our center from January 2000 to January 2019 were included in this study. We retrospectively collected information on sex, age, history of smoking, family history of cancer, comorbidities, symptoms, imaging tests, serum tumor marker levels, tumor, node, metastasis (TNM) staging, and treatment records. Follow-up information was obtained by telephone interviews or outpatient clinic visit. Univariate and multivariate Cox regression analyses were performed to investigate the clinicopathological factors associated with survival.

RESULTS

Among 14 patients with PTAC, there were five males and nine females, with an average age of 48.7 ± 9.3 years. A total of 23.1% of the patients had a history of smoking. The clinical symptoms of the patients were nonspecific and seven patients had elevated levels of serum tumor markers. Surgery was performed for nine patients, among which only four received R0 resection. The median survival time of the 14 patients was 16.0 months, and the 1-, 3- and 5-year survival rates were 57.1%, 35.7% and 21.4%, respectively. TNM stage was identified as an independent prognostic factor for PTAC patients (the median survival time of stage I-IIIA vs. stage IV was 44.0 months vs. 9.0 months, p = 0.002).

CONCLUSIONS

PTAC is highly aggressive malignancy with poor prognosis. Surgical treatment is feasible, but R0 resection is challenging. TNM staging is significantly associated with patient survival.

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.

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.

Lenvatinib-refractory thymic mucinous carcinoma with PIK3CA mutation

Mucinous adenocarcinoma, a very rare type of thymic carcinoma, is aggressive and has a poor prognosis. The optimal treatment for advanced thymic mucinous adenocarcinoma has not yet been established because of its rarity. An oral multi-tyrosine kinase inhibitor, lenvatinib, was approved for treatment of thymic carcinoma in March 2021 in Japan. However, to the best of our knowledge, there are no published reports concerning lenvatinib for thymic mucinous adenocarcinoma. Herein, we report a 39-year-old woman who presented with a 70 mm multilocular cystic tumor in her left anterior mediastinum and a massive pericardial effusion. We diagnosed a Masaoka stage IVb thymic mucinous adenocarcinoma with multiple metastases to the liver and bones, and pericardial dissemination on the basis of the pathologic findings on examination of a video-assisted thoracoscopic tumor biopsy and radiological examinations. She received paclitaxel-carboplatin-based chemotherapy, but developed a left cerebellar metastasis. Second-line chemotherapy with lenvatinib failed to suppress the tumor. She died of cancer progression 5 months after presentation. Here, we report what we believe to be the first case of a thymic mucinous adenocarcinoma treated with lenvatinib. Our patient's thymic mucinous adenocarcinoma was refractory to both cytotoxic chemotherapy and lenvatinib. Using next-generation sequencing, we identified phosphatidylinositol 3-kinase catalytic subunit alpha mutation in the tumor. We suspected an association between this mutation and resistance to lenvatinib. We therefore recommend performing next-generation sequencing when considering introduction of lenvatinib for thymic mucinous adenocarcinoma. A surgical procedure may be necessary for accurate diagnosis and genetic analysis of this histological tumor type.

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.

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.

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.

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.

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.

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 mucinous adenocarcinoma of the posterior mediastinum

We report a rare case of primary mucinous adenocarcinoma of the posterior mediastinum. A 36-year-old man was referred to our hospital with right flank pain. Computed tomography showed a cystic mass in the posterior mediastinum, and the tumor displaced the diaphragm downward and the inferior vena cava forward. The patient underwent extirpation of the tumor. The cut surface of the resected tumor showed a unilocular cyst filled with abundant gray gelatinous fluid. Microscopically, the tumor had a fibrous capsule lined with cuboidal and columnar malignant epithelial cells with intracellular mucin accumulation and was diagnosed as a mucinous adenocarcinoma.

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.

Thymic carcinoma, part 1: a clinicopathologic and immunohistochemical study of 65 cases

The clinicopathologic and immunohistochemical features of 65 primary thymic carcinomas are reported (43 men and 22 women; 19-81 years old). Thymectomy was performed in all cases. Masaoka staging for 53 patients showed 3 patients in stage I, 14 in stage II, 17 in stage III, and 19 in stage IV. Histologic studies revealed 9 carcinoma subtypes. Immunohistochemically, the tumors showed high rates of expression for cytokeratin, Pax8, and FoxN1. Follow-up for 62 patients revealed that 36 patients were alive (mean follow-up, 51.1 months) and 26 had died (mean survival, 47.5 months). The 3- and 5-year overall survival rates were 76.6% and 65.7%, respectively. Our findings suggest that thymic carcinomas may behave less aggressively than commonly believed. Lymph node status and tumor size seem to be important prognostic factors. The Masaoka staging system does not seem to reliably predict outcome.

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.