A 36-year-old woman presents with swelling in her neck that she first noticed 3 months ago. She also complains of intermittent watery diarrhea over the same time period. Physical examination reveals a nontender nodule in the left lobe of the thyroid. The patient's mother died of thyroid cancer 8 years ago. The thyroid nodule is found to be "cold" by radioiodine scintiscan. A needle biopsy of the nodule reveals malignant cells and homogeneous eosinophilic material The tumor in the patient described in Question 38 is removed, and a section stained with Congo red reveals birefringent amyloid stroma. Genetic studies show that this patient has a familial cancer syndrome. In addition to hyperparathyroidism, the patient is advised that she is at risk of developing which of the following neoplastic diseases?