Polyserositis revealing a signet ring cells gastric adenocarcinoma in a 27 years old male patient: A case report.

Gastric cancer remains one of the most common and deadly cancers worldwide, especially among old males. It is rare in the younger population (< 30 years old). We describe the case of a 27 years old male patient, presenting to the emergency department, with exsudative polyserositis, initially misdiagnosed and treated as a multifocal tuberculosis with no clinical improvement, later revealing a metastatic signet ring cells gastric adenocarcinoma.


Introduction
Gastric cancer is the 5th most common neoplasm and the 3rd most deadly cancer with an estimated 783000 deaths [1]. Over one million cases of gastric cancer are diagnosed each year around the world, especially among old males (60-70 years old) [1]. Early diagnosis and treatment have shown to improve survival rate although very non satisfying in the metastatic stage [2].
Gastric adenocarcinomas are primarily classi ed as cardia and non-cardia based on their anatomic site.
Cancers of the gastric cardia arise in the region adjoining the esophageal-gastric junction and thus share epidemiological characteristics with esophageal adenocarcinoma (smoking, alcohol, obesity, gastroesophageal re ux…). Non-cardia cancer, also known as distal stomach cancer, arises in the lower portion of the stomach, and Helicobacter Pylori infection represents it's most important risk factor [1][2][3][4].
Although non-cardia cancer is more common than cardia cancer, the incidence of the latter has increased 7 times these past decades [3]. Gastric cancer is common among old patients. However, only a few cases have been reported in the younger population [4].
We hereby describe the case of a 27 years old male patient, presenting to the emergency department with exsudative polyserositis ( bilateral pleural effusion and ascites), initially misdiagnosed and treated as a multifocal tuberculosis with no clinical improvement. Patient was admitted in the infectious diseases department for further investigations, later revealing a metastatic gastric signet ring cells adenocarcinoma.

Observation
It's a 27 years old male patient, with no medical history, who started complaining, 10 months prior to his admission, of epigastric pain, dyspepsia and post-prandial nausea and vomiting, for which he received a simple symptomatic treatment. Seven months later, patient presented a dry cough, a mild abdominal distension and bilateral basithoracic pain along with his initial symptoms, which made him consult his doctor.
A chest X-ray was performed and showed bilateral pleural effusion. The patient then received antibacillary treatment for 45 days (documents to support the diagnosis of a multifocal tuberculosis couldn't be found). Even thought he received his treatment correctly, the patient noticed no clinical improvement (frequent dry cough, important abdominal distention, signi cant weight loss, and shortness of breath), which made him stop all medication and present to the emerging department. The initial diagnosis of a multifocal tuberculosis was questioned because of this clinical outcome, hence his admission in the infectious diseases department for further investigations.
Clinical examination showed a pale patient with stable hemodynamics and mild dyspnea. Weight: 58 kgs .Urines were dark colored, and a Labstix test performed on a urine sample showed proteinuria (+) and hematuria (++). We also brought out a bilateral pleural effusion syndrome (inferior half of the right lung and inferior 1/3rd of the left lung), Ascites (abdominal distention and dullness to percussion), bilateral lower limb edema, and no palpable lymph node.
An EKG was performed and showed a sinus tachycardia and no electrical signs of heart failure. Blood and urine tests results are summarized in Table 1, ascites and pleural effusion puncture tests results are summarized in Table 2.  An esophago-gastro-duodenoscopy (EDG) was performed to explore his digestive discomfort, and showed a tumor in the greater curvature of the stomach invading the cardia. Tumor biopsy and histological examination only revealed sub-acute in ammation stigmates. A second EDG with biopsy showed an undifferenciated gastric adenocarcinoma with signet ring cells components. Figure 1 and Fig.  2. A fragment of the tumor biopsy was saved for direct examination and culture of Mycobacterium tuberculosis in a Loweinstein Jensen Medium, which came back negative. For cancer staging, the patient underwent a CT-scan examination which showed a circumferential gastric wall thickening with important ascites and bilateral pleural effusion, making it a metastatic stage IV gastric adenocarcinoma.
Patient was programmed to undergo neo-adjuvant chemotherapy (XELOX protocol): oxaliplatine + capecitabine, but unfortunately died a few days later before he could receive any treatment.

Discussion
Gastric cancer is common among old patients and very rare in the young population (< 30 years old) [5,6]. Non-cardia gastric cancer incidence has decreased over the past ve decades thanks to better food hygiene and preservation, Helicobacter Pylori eradication and the systematic mass screening in some countries [2,7]. However, cardia gastric cancer incidence is increasing [8]. We underline a higher incidence levels in Japan, China, Latin America versus lower incidence levels in North African countries, which may suggest the role of geographic location in the incidence of gastric cancer [2]. Gastric adenocarcinoma is the most common histological type of gastric cancer (95%). Signet ring cells adenocarcinoma is a very rare and exceptional entity in the subjects younger than 30 years old [1,5].
Histological classi cation of gastric carcinoma has been largely based on Lauren's criteria [9], in which gastric cancer is classi ed into two major histological subtypes :Intestinal type commonly seen among old patients, and diffuse type, which was the case of our patient, commonly seen among young patients and generally associated with poor prognosis [4,9]. Gastric cancer in young patients is more aggressive, and often diagnosed at a late metastatic stage, it is more common among females versus males [4,6], as opposed to gastric cancer in the older population where it is more common among males. [7,10,11]. Our patient presented a gastric cancer located in the greater curvature of the stomach with cardial invasion.
Cardial location is more common in the young population compared to old subjects (33%) and represents a poor prognosis risk factor [10,12]. Siwert et al de ned 3 types of cardia gastric cancer [13], our patient is a Siwert type 3.
Gastric adenocarcinomas are oftenly misdiagnosed due to the lack of clear symptoms and low frequency in the young population [4,6,7,14]. Gastrointestinal tract related symptoms such as epigastric pain, dyspepsia and vomiting must be explored regardless of the patient's age [15]. Our patient initially had the same symptoms before developing an exsudative polyserositis, which was misdiagnosed and treated as multifocal tuberculosis. We would like to point out the importance of a thorough follow up with patients who receive antibacillary treatment, and the lack of clinical improvement should help practitioners question their diagnosis and conduct further investigations.
Gastric cancer metastasis are primarily represented by lymph nodes, liver, spleen, pleura, lungs, and peritoneum [16], peritoneal metastasis are more common in the young subjects [7]. Our patient had bilateral pleural effusion and ascites probably metastatic (Exsudative effusion with 80% lymphocytes in the cell count) although we couldn't con rm their origin.

Conclusion
This case sheds the light on gastric cancer in the young subject, oftenly unknown in this population, and diagnosed at a late metastatic stage, which is usually associated with a poor prognosis. Symptoms such as dyspepsia, nausea, vomitting, epigastric pain, deserve to be explored regardless of the age, in order to avoid misdiagnosing one of the most common and deadliest malignancies worldwide.

Declarations
Funding Not applicable

Con icts of interest
The authors declare no con ict of interest  Figure 1 A low magni cation (10x) pathology image: gastric mucosa is the site of an in ltrating carcinomatous proliferation arranged in clusters, strings and isolated cells.