USMLE® Step 1 style questions USMLE
A newborn male infant is admitted to the neonatal intensive care unit because of acute respiratory distress. The baby was prematurely born to a gravida 1, para 0, mother via cesarean section following an uncomplicated pregnancy. Relevant medical history shows a previous antenatal sonography that revealed multiple cerebral, kidney, and heart lesions. The baby had an Apgar score of 1 at birth. Physical exam shows acrocyanosis and a heart murmur. His temperature is 36.7°C (98°F), the pulse is 148/min, respirations are 60/min, blood pressure is 53/27 mmHg, and pulse oximetry on room air shows an oxygen saturation of 50%. He dies 3 hours later after his admission. The autopsy revealed multiple tumor masses in the interventricular septum and ventricular walls of the heart. Which of the following is the most likely related association with this patient’s condition?
Cardiac tumors are abnormal growths of cells that form a mass in the heart. If the cell growth has the potential to invade and spread to other tissues — a process called metastasis — it’s a malignant tumor, more commonly known as a cancer. If it is not able to invade other tissues, it’s referred to as a benign tumor.
Now, the vast majority of tumors of the heart are actually secondary, meaning that a tumor developed somewhere else in the body, metastasized, and spread to the heart.
Even though these secondary tumors can come from anywhere, they’re most commonly metastases from lung cancer, lymphoma or lymphatic system cancer, breast cancer, leukemia or blood cell cancer, melanoma or skin cancer, hepatocellular carcinoma or liver cancer, and colon cancer, in this order. Cancer most commonly metastasizes through the lymphatic system to the pericardium, the membrane around the heart. When the pericardium is involved, it often leads to pericarditis, or inflammation of the pericardium, and pericardial effusion, an accumulation of fluid in the pericardial cavity. Metastases to the myocardium are less common, but arise more commonly when cancer spreads via the blood.
Primary cardiac tumors, on the other hand, are actually extremely rare. The most common type of primary tumors in adults — when they do happen — are myxomas. Myxomas are benign tumors that arise from the mesenchymal connective tissue inside the heart, as opposed to the actual myocytes, or heart cells, because the heart of an adult is fully developed and its cells, or myocytes, are permanent and don’t proliferate.
These masses are gelatinous in consistency, as a result of an abundance of ground substance on histology, and pedunculated, meaning attached to a peduncle, or a stalk of tissue.