Salivary carcinosarcoma: insight into multistep pathogenesis indicates uniform origin as sarcomatoid variant of carcinoma ex pleomorphic adenoma with frequent heterologous elements.

AIMS: The formal pathogenesis of salivary carcinosarcoma (SCS) remained unclear, both with respect to the hypothetical development from either preexisting pleomorphic adenoma (PA) or de novo and the clonal relationship between highly heterogeneous carcinomatous and sarcomatous components. METHODS AND RESULTS: We performed clinicopathological and molecular (targeted RNA sequencing) analyses on a large series of 16 cases and combined this with a comprehensive literature search (111 cases). Extensive sampling (average 11.6 blocks), combined with immunohistochemistry and molecular studies (PA-specific translocations including PLAG1 or HMGA2 proven in 6/16 cases), enabled the morphogenetic identification of PA in 15/16 cases (93.8%), by far surpassing a reported rate of 49.6%. Furthermore, we demonstrated a multistep (intraductal/intracapsular/extracapsular) adenoma-carcinoma-sarcoma-progression, based on two alternative histogenetic pathways (intraductal, 56.3%, versus myoepithelial pathway, 37.5%). Thereby, early intracapsular stages are identical to conventional carcinoma ex PA, while later extracapsular stages are dominated by secondary, frequently heterologous sarcomatous transformation with often large tumour size (>60 mm). CONCLUSION: Our findings strongly indicate that SCS (almost) always develops from PA, with a complex multistep adenoma-carcinoma-sarcoma-sequence, based on two alternative histogenetic pathways. The findings from this novel approach strongly suggest that SCS pathogenetically is a rare (3-6%), unique, and aggressive variant of carcinoma ex PA with secondary sarcomatous overgrowth. In analogy to changes of terminology in other organs, the term "sarcomatoid carcinoma ex PA with/without heterologous elements" might be more appropriate.

Thyroid Metastasis From Caecal Adenocarcinoma.

The thyroid is a rare site of colorectal metastasis, comprising 0.1% of the surgical case series. A 62-year-old woman with caecal adenocarcinoma and previously surgically resected lung and liver metastases presented incidentally with a right thyroid nodule, which had grown and become symptomatic. Imaging revealed the nodule to have extracapsular spread, and cytology demonstrated metastatic adenocarcinoma. The patient underwent a technically challenging right thyroidectomy and neck dissection, with the final histopathological review demonstrating metastatic adenocarcinoma from a colorectal primary. The patient has subsequently undergone adjuvant radiotherapy. This case highlights an uncommon source of metastasis to the thyroid, which may aid clinicians to recognise and initiate treatment. It also highlights the technical challenges of performing surgery in such cases.

Cystic Squamous Cell Carcinomas of the Jaws: Twelve Cases Highlighting Histopathological Pitfalls.

Cystic squamous cell carcinomas (SCCs) of the jaws, including carcinoma cuniculatum, are rare, slow growing, and relentlessly invasive. The aim of this article is to present 12 cases, 4 of which were designated as carcinoma cuniculatum on the basis of deeply endophytic, anastomosing channels of cystic stratified squamous epithelium and keratin microabscesses. The other 8 were also cystic, but more heterogeneous morphologically and were diagnosed as well differentiated SCCs. Six patients were female, 6 were male (mean age = 74.0 years, range = 50-94 years). Six tumors affected the mandible, 6 the maxillary alveolus with or without extension into the hard palate. All patients underwent primary resection with neck dissection and were staged as T4a N0 M0. In 4 patients, diagnosis was delayed as a result of superficial biopsies and/or confusing histopathology. Cystic SCCs of the jaws can be difficult to diagnose and clinicoradiological correlation is essential. Long-term follow-up is mandatory.

Mistaken identity: endometrial or rectal cancer?

A 59-year-old woman with a previous history of endometrial and breast cancer was referred to the colorectal rapid access clinic with abdominal cramps, per rectal bleeding and diarrhoea. CT, MRI and flexible sigmoidoscopy confirmed a rectal tumour and due to its appearance, it was thought to be a primary rectal malignancy. The patient underwent an anterior resection and end colostomy. Histology confirmed a metastatic endometrial adenocarcinoma, which is an unusual site for endometrial metastasis. Her postoperative recovery has been unremarkable and the patient has subsequently been discharged from the general surgical team.