Academic Editor: Divey Manocha
Affilation: Upstate Medical University
Adenosquamous carcinoma of the stomach (ASCS) is extremely rare with less than one hundred cases published in the world literature. It is defined by combined adenocarcima and squamous cells carcinoma of the stomach. ASCS is clinically aggressive and has a poor prognosis, even when discovered at an early stage. This intriguing entity is characterized by non specific symptoms or radiological signs. Integrate 18F-fluorodeoxyglucose positron emission tomography/computed tomography 18F FDG.PET/CT is useful morphologic and functional modalities for evaluating primary tumor, local extend and invasion beyond gastric wall or distant metastatic and eventually for management. Diagnosis of ASCS requires immunohistochemical confirmation. We report a 77-year-old man who was admitted to hospital because of epigastric pain, vomiting and melena since more than a month. Gastroscopy with biopsies had initially suggested gastric squamous cell carcinoma .Thoracic and abdominal computed tomography scan (CT) showed a huge mass in the gastric body, largely necrotic, infiltrating the adjacent structures without metastases. Partial gastrectomy with resection of the proximal 2/3 of the stomach, the spleen, the body and tail of pancreas and the left transverse colon was performed. Immunohistochemical analysis demonstrated ASCS with mixed adenocarcinomatous and squamous cells carcinoma with invasion of gastric lymph nodes. Unfortunately, two months after surgery, a CT of the abdomen revealed diffuse metastasis and the patient died three months later.
In light of this case, we discuss the pathogenesis, staging and monitoring of this rare entity by combined 18F-FDG PET/CT with review of the literature.
Adenosquamous carcinoma (ASCS) is an exceedingly rare neoplasm of the stomach. This tumor consists in varying proportions of adenocarcinoma and squamous cell carcinomas. The incidence of this entity varies between 0, 04 and 0, 07% of gastric cancer and less one hundred cases are described in the literature. We present one case of ASCS in a 77 year-old man. In light of this observation we discuss than several hypothesis of pathogenesis and the fundamental role of combined fluorine-18 fluorodeoxyglucose imaging PET and computed tomography (18F-FDG.PET/CT) in staging and monitoring this unusal tumor.
Among carcinomas of the stomach, adenocarcinomas are the most prevalent type, and adenosquamous carcinoma (ADSC) or squamous cells carcinoma are excedentely rare representing respectively 0.07 and 0, 04 % of all gastric carcinomas, according to the WHO criteria of histological classification of stomach tumors
ASCS consists a mix of varying proportion of adenocarcima cells and squamous cells carcinoma, but the later component by definition should exceed 25% of tumor gastric mass
Many authors now believe that this kind of carcinoma results from two theories, either transforming or collision
Furthermore, Boswell and Helwig
In spite of that, the exact histogenesis of the ASCS is not yet clear; however, multiple hypotheses are postulated
Our present case seems to support these hypotheses theories for 4 reasons: the tumor showed keratinizing cell masses, mosaic patterns, intercellular bridges and adenocarcinoma components.
Preoperative diagnosis of ASCS of the stomach is difficult and is challenging. There are no specific clinical symptoms or defining radiological imaging that would differentiate this neoplasm from the more common gastric tumors.
The symptoms are nonspecific including vague abdominal pain, melena, diarrhea and weight loss
The American Joint Committee on Cancer (AJCC), staging system is widely used for the characterization of disease, burden and prognosis in gastric cancer
Over the last two decades, thin section with multiplanar reconstruction CT scan combined to 18F-FDG PET have dramatically increased the impact of management of gastric tumors at different stages. Correlating anatomic information and functional modalities help for diagnosis, pre operative staging of the ASCS and for monitoring treatment effect.
CT scan is an accurate anatomical imaging for determination of preoperative T stage. In spite, 18F-FDG PET cannot be helpful in determinated the exact T stage because prominent uptake averaged across several millimeters, a distance too great to give confidence when assessing barrier invasion on the surface of organs such as present case
Moreover, CT Scan identify positive lymph nodes metastasis based on size, shape, central necrosis and heterogeneity confirms metastatic involvement in stage I and II but cannot distinguish between reactive hyperplasia or metastatic enhancement
For metastases, 18F FDG PET may be more accurate than the anatomical imaging modalities in the detection of metabolic distant metastases, and liver metastases smaller than 1 cm missed during the portal venous or arterial phase on CT scan
Despite technical advances in gastroenterology and imaging in the early detection of ASCS, the diagnosis is often made after the tumor has already metastasized to the regional and distant lymph nodes, liver or lung, such as in our patient. Accurate preoperative diagnosis of ASCS is made with great difficulties since there are no imaging studies that would differentiate it from squamous cell carcinoma, adenocarcinoma, lymphoma, gastrointestinal stromal tumor (GIST) or more benign stomach neoplasm
Complete resection of the gastric tumor and adjacent lymph nodes represents the only effective curative treatment
Despite the recent advances in diagnosis and therapy, the mortality with ASCS sremains substantial. Patient's outcome after resection of ASCS is generally poor. The typically advanced stages at the time of initial diagnosis explain this outcome. ADSC of the stomach is more aggressive than other histological types of gastric carcinomas
It is not surprising that survival was not prolonged in our patient who had an ASCS and a rapid systemic metastasis less than three months after.
The ASCS is a rare malignancy, characterized by a particularly aggressive potential and poor prognosis. It is often found at the stage of digestive complications with extensive visceral invasion and metastasis. Early diagnosis of ASCS has important implications for surgical management at presentation and afterward. The combined use of CT and 18F-FDG PET may be useful in the preoperative staging and helpful in the follow up of patients undergoing chemotherapy but the diagnosis remains based on immunohistochemical exams.