Introduction: Parathyroid carcinoma (PC) is an extremely rare entity, with a frequency of 0.005% of all malignancies. Most data related to this rare disease are limited to case series and a few database studies. We present a large database study that aims to investigate the demographic, clinical, and pathological factors, prognosis, and survival of PC. Methods: Data of parathyroid carcinoma were extracted from the Surveillance, Epidemiology, and End Results (SEER) diagnosed between 1975 and 2016. Results: PC had a slightly higher incidence in men (52.2%, p < 0.005), the majority of cases affected Caucasians (75.4%, p < 0.005), and the mean age at diagnosis was 62 years. Histologically, 99.7% were adenocarcinomas not otherwise specified (p < 0.005), well-differentiated (p < 0.005), and 2–4 cm (p < 0.001) in size among the patients with available data. In cases with staging provided, most PC were organ-confined (36.8%, p < 0.001). Lymph nodes were positive in 25.2% of cases where lymph node status was reported. The main treatment modality was surgery (97.2%), followed by radiation alone (2%), and very few received chemotherapy alone (0.8%), p < 0.005. Five-year follow-up was available for 82.7% of the cases. Those who underwent surgery only or radiation alone had 5-year survivals of 83.8% and 72.2%, respectively (p < 0.037). Multivariable analysis identified tumor size >4 cm, age > 40 years, male sex, Caucasian race, distant spread, and poorly differentiated grade as independent risk factors for mortality (p < 0.001). Conclusion: PC is a very rare tumor mostly affecting Caucasian individuals in the fifth decade. Older age, poor histologic differentiation, and distant metastasis are associated with a worse prognosis. Surgical resection offers the best survival outcome. To better understand the pathogenesis and factors affecting survival, all PC patients should be enrolled in national and international registries.

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SARS-CoV-2 is responsible for causing the COVID-19 pandemic and over 4 million deaths globally. Clinical symptoms range from asymptomatic infection, viral syndrome, and pneumonia, to acute respiratory distress syndrome. Guillain-Barre syndrome (GBS), an acute demyelinating inflammatory polyneuropathy, may be a manifestation of infection and must be recognized quickly by clinicians to avoid neurological deterioration in these patients. Here, we present an interesting case of GBS in a patient with a previous COVID-19 infection. A 63-year-old male with a past medical history of hypertension, chronic obstructive pulmonary disease, obesity, and recent COVID-19 infection just five weeks prior to the presentation without COVID-19 vaccination presented to a family medicine clinic due to a history of falls as well as lower extremity numbness, weakness, and paresthesias for the past 36 hours. The patient’s MRI and lumbar puncture were unremarkable and the patient was transferred to a tertiary care center. The patient was diagnosed with GBS secondary to his COVID-19 infection five weeks prior. He received a standard five-dose regimen of 400 mg/kg/day of intravenous immunoglobulin and demonstrated rapid improvement in response to therapy. Temporal factors associated with disease such as the seemingly delayed onset of symptoms after COVID-19 viral infection in comparison to other cases of GBS, as well as the rapid progression of symptomatology, are of note. Healthcare providers should still consider GBS as a possibility in patients with a relatively distant history of COVID-19 infections. Rapid progression of symptoms should also be monitored as this may result in earlier respiratory morbidity and mortality in the absence of appropriate diagnosis and treatment.