This initial Literature serious spontaneous case, was received from health professional (Physician) on 25-Sep-2017, concerning a 09-year-old male child patient. On an unspecified date, the patient was administered with influenza vaccine, (dose, route of administration, anatomical location, batch number, expiry date, manufacture and trade name was not provided). A 9-year-old otherwise healthy male presented to the emergency department (ED) with 3 weeks of decreased energy, decreased appetite, and a 2-week history of persistent cough. The patient was initially seen at an outside hospital ED 2 weeks before this most recent ED visit, predominantly for cough, and was discharged home with albuterol without a specific diagnosis. Two days after his initial ED visit, he went to see his primary care physician, was diagnosed with croup, and prescribed a 5-day course of dexamethasone. On an unspecified date, after the administration of vaccine, the patient started coughing again, predominantly at night. Three days prior, he was seen again by his primary care physician and was diagnosed with mycoplasma pneumonia. On the same day, a rapid strep was sent and it was negative. The patient was started on a 5-day course of azithromycin but had persistent and worsening cough. The morning of his visit to the ED, the patient was seen by his primary care physician and was given an albuterol treatment, which helped his cough. He was noted to be febrile to 101-degree F at his physician's office. This was the first time during his course of illness that he had a fever. His cough was now also associated with rhinorrhea and mild sore throat. On an unspecified date, chest x-ray (CXR) was performed, which showed right lower lobe pleural effusion. On review of systems, he denied any chest pain, abdominal pain, nausea, vomiting, diarrhea, constipation, rashes, myalgia, arthralgia, weight loss, or night sweats. He had no recent travel or sick contacts, and there was no known human immunodeficiency virus or tuberculosis exposure. He was living with his mother who did not know his complete past medical history, but she stated that he was healthy, his immunizations were up to date, and he did not have any known allergies. His family history was unknown. He was taking albuterol as needed for cough and was on day 3 of 5 of azithromycin when he presented to ED for further evaluation. On an unspecified date in initial examination, he was well appearing and active but noted to be coughing frequently. His vital signs revealed a temperature of 37.20 degrees C, a heart rate of 106 beats per minute, a respiratory rate of 32 breaths per minute, a blood pressure of 95/62 mmHg, and an oxygen saturation of 97% on room air. His weight was 36.9 kg. His head and neck exam was notable only for mild rhinorrhea. He had full range of motion at the neck with no evidence of cervical lymphadenopathy. On an unspecified date, cardiac examination was performed, which showed a regular rate and rhythm, a harsh 2/6 systolic murmur at the left lower sternal border with no evidence of rubs or gallops, and normal central and peripheral pulses. It was reported that, the patient's family was not aware that he had a heart murmur. On an unspecified date, on pulmonary examination, the patient had coarse breath sounds bilaterally with intermittent crackles and decreased breath sounds in the right lower lobe, without increased work of breathing or tachypnea. He had a persistent dry cough, worse when supine, with significant orthopnea. No axillary lymphadenopathy was noted. His abdomen was soft, non tender, and with normal bowels sounds. There was no hepatosplenomegaly, but slight generalized voluntary guarding was noted. On an unspecified date, genito-urinary examination was performed which was unremarkable, and there was no noted inguinal lymphadenopathy. On an unspecified date, musculoskeletal examination was performed, where the patient had a normal gait, full range of motion at all joints, and no evidence of edema or swelling. On an unspecified date, neurological examination was performed, where the patient had no focal neurological deficits and his cranial nerves were intact laboratory evaluation was significant for a white blood cell count of 14,600 (with 66% segmented neutrophils, 22.7% lymphocytes, and 9.5% monocytes). His hemoglobin was 12 g/dL, and his hematocrit was 34%. Platelets are within normal limits at 312,000 per micro liter. Inflammatory markers were elevated with a C-reactive protein of 6.2 mg/dL and an erythrocyte sedimentation rate of 108 mm/h. Coagulation studies were within normal limits: prothrombin time, 11.8 seconds, international normalized ratio, 1.8; and partial prothrombin time, 26 seconds. Lactic dehydrogenase was elevated at 1078 U/L, and uric acid was within upper limits of normal at 5.4 mg/dL. Electrolytes were within normal limits, as were his bilirubin and liver transaminase. His previously obtained CXR was solely an anterior/posterior view. On an unspecified date, CXR (X ray) with both anterior/posterior and lateral was performed again noted the right lower lobe pleural effusion as well as the right round paratracheal/anterior mediastinal mass with a slight leftward shift of mediastinal structures. On an unspecified date, computed tomography (CT) scan of the chest, abdomen, and pelvis was performed, which showed a heterogeneous anterior mediastinal mass causing significant tracheal narrowing and deviation. The left innominate and subclavian veins were not seen, likely owing to mass effect. A moderate size right pleural effusion and a small pericardial effusion were also noted. In addition, there was narrowing of the superior vena cava. No abdominal or pelvic abnormalities were noted. This constellation of findings was consistent with malignant neoplasm with lymphoma the most likely etiology. During his ED course, the patient had episodes of unrelenting cough, stating that he was unable to catch his breath. During these episodes, he would be tachycardic to the 150 seconds and his saturation would decrease to 90% on room air. He was extremely anxious and agitated. Oxygen was administered via a non-rebreather mask, subsequent to which the patient calmed down and had improved vital signs. Once calm, he was weaned back to room air and maintained oxygen saturations around 93% to 95%. He was given nebulized saline and racemic epinephrine treatments, which seemed to alleviate his symptoms. He was transitioned to 1 L of oxygen via nasal cannula, and his oxygen saturation rose to 98%. Oncology was consulted, and at that time, there was discussion about pursuing emergent radiation versus observing the patient after initiating high dose steroids. Given his inability to tolerate the supine position, he was admitted to the pediatric intensive care unit on high-dose steroids. Allopurinol and rasburicase were given before steroids to reduce the risks of tumor lysis syndrome and major electrolyte instability. At the time of admission to the pediatric intensive care unit, he was noted to be alert but ill appearing and pale, with mild tachypnea and tripod positioning. A pleurocentesis performed on hospital day number 1 was diagnostic for T-cell lymphoblastic lymphoma. He was started on chemotherapy according to protocol. Additional initial workup included an echocardiogram, which was within normal limits. He was discharged on hospital day number 14 on continued chemotherapy and initially did well. Unfortunately, he died from complications of his disease 7 months after his initial diagnosis. Autopsy performed was unknown Croup was initially on the primary care physician's differential; however, croup is not a common diagnosis for children in this age group. Often, imaging is obtained in these instances if croup is diagnosed. With his recent onset of fever, a significant bacterial infection such as an empyema or viral influenza was unlikely, but a viral pneumonia was still a possibility, especially with evidence of pleural effusions on his most recent CXR. In assessing the complete blood count, tuberculosis is less likely with a normal lymphocyte percentage and pertussis is less likely with the lack of monocytosis.