A Rare Case of Tumor-to-Tumor Metastasis: Renal Cell Carcinoma Metastasis to Papillary Thyroid Carcinoma.

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy. Renal cell carcinoma (RCC) metastasis to the thyroid, albeit the most common carcinomatous metastasis to the thyroid, is rare, and tumor-to-tumor metastasis of RCC to PTC is even rarer. We present a case of a 65-year-old male with a history of RCC who presented with a thyroid nodule 7 years after left radical nephrectomy. Imaging showed the thyroid nodule predating the kidney tumor. Fine-needle aspiration biopsy was performed and showed 2 distinct cell populations, 1 of which was stained with RCC markers and another that was stained positively for thyroid markers. An interpretation of atypia of undetermined significance was rendered and molecular testing was indeterminate with ThyGeNEXT not detecting mutations and ThyraMIR positive for a level 2 microRNA pattern consistent with low risk for malignancy. The patient elected for active surveillance until follow-up thyroid ultrasound showed continued growth. At this point, a right hemithyroidectomy was performed. Pathology confirmed clear cell RCC metastasis to an infiltrative follicular variant papillary thyroid carcinoma. This case highlights the possibility of tumor-to-tumor metastasis in patients with a previous history of RCC even years after nephrectomy and in the absence of other metastatic lesions.

Kounis syndrome following beta-lactam antibiotic use: review of literature.

BACKGROUND: Patients with anaphylaxis can have acute coronary syndromes secondary to allergic mediator effects on coronary vessels. Information about these cases is restricted to isolated case reports. METHODS: To review this topic we identified all cases in the PubMed database in English with searches using beta-lactams\adverse effects and several coronary disease MeSH terms. RESULTS: We analyzed 17 cases with a median age of 60 (range 13 to 72). Seventy-six percent of the patients were men. The beta-lactam antibiotic was administered by oral, IV, and intramuscular routes. Thirteen patients had cutaneous reactions, seven had respiratory symptoms, two had GI symptoms, 11 had chest pain, and 12 had hypotension. All reactions except one developed within 30 minutes. Ten patients had an elevated troponin levels. ECG revealed ST segment elevation in all patients except one. Cardiac catheterization was normal in 10 patients and abnormal in five patients. Allergy testing identified four patients with positive skin tests to antibiotics, four with increased IgE levels, three with increased histamine and tryptase levels, and one with a positive leukocyte transformation test. Treatment included drugs for anaphylaxis and acute coronary syndrome. All patients survived. CONCLUSIONS: Patients with anaphylaxis can present with acute coronary syndrome secondary to either vasospasm or acute plaque rupture and thrombus formation. The typical patient is a man with cutaneous, respiratory and cardiac symptoms and with ST segment elevation in inferior leads. The pathogenesis involves histamine and other mast cell mediators. Management should include therapy for anaphylaxis and vasospasmolytics. The use of epinephrine requires caution.