Ectopic Parathyroid Tumor
Key Facts
Clinical Issues
Incidence
Among the rarest neuroendocrine tumors in mediastinum
Usually in adults
Symptoms
Chest pain
Cough
Dyspnea
Hyperparathyroidism
Kidney stones
Top Differential Diagnoses
Well-differentiated neuroendocrine carcinoma (carcinoid tumor)
Neuroendocrine carcinoma and ectopic parathyroid tumors may share similar immunophenotype
Parathyroid hormone immunohistochemistry is more commonly seen in ectopic parathyroid tumors
Paraganglioma
Generally negative for keratin stains
Thymic carcinoma
Negative for neuroendocrine markers, including parathyroid hormone
Diagnostic Checklist
Symptom complex
Oncocytic cellular proliferation
Chief cells
Mixed oncocytic and chief cells
In adenomas, lack of mitotic activity
In carcinomas, presence of mitosis, hemorrhage, &/or necrosis
 Low-power view shows an ectopic parathyroid adenoma of the mediastinum. The histology recapitulates the features of a normal parathyroid tissue. |
 High-power view of a parathyroid adenoma of the mediastinum is shown. The tumor shows a striking neuroendocrine morphology with a homogeneous cellular proliferation. |
TERMINOLOGY
Definitions
Neuroendocrine tumors of mediastinum
ETIOLOGY/PATHOGENESIS
Developmental Anomaly
Misplacement of normal glands in anterior mediastinum
CLINICAL ISSUES
Epidemiology
Incidence
Among rarest neuroendocrine tumors in mediastinum
Age
Usually in adults
Gender
No gender predilection
Site
Anterior mediastinum
Presentation
Chest pain
Cough
Dyspnea
Hyperparathyroidism
Kidney stones
Laboratory Tests
Calcium, phosphorus
Treatment
Surgical approaches
Complete surgical resection
Adjuvant therapy
In cases of ectopic parathyroid carcinoma
Prognosis
Good in cases of parathyroid adenoma
IMAGE FINDINGS
General Features
Anterior mediastinal tumor
MACROSCOPIC FEATURES
General Features
Light brown, soft tissue tumor
Hemorrhage and necrosis may be present
Size
Variable and can reach over 10 cm in diameter
MICROSCOPIC PATHOLOGY
Histologic Features
Oncocytic cellular proliferation
Chief cells
Mixed oncocytic and chief cells
Mild nuclear atypia
Mitotic figures in cases of carcinoma
DIFFERENTIAL DIAGNOSIS
Well-differentiated Neuroendocrine Carcinoma (Carcinoid Tumor)
Neuroendocrine carcinoma and ectopic parathyroid tumors may share similar immunophenotype
Parathyroid hormone immunohistochemistry is more commonly seen in ectopic parathyroid tumors
Clinical presence of disturbances in calcium metabolism are more in keeping with parathyroid tumors
PAS is more likely to show positive staining in parathyroid tumors
Paraganglioma
Generally negative for keratin stains
Show more nuclear pleomorphism
Thymic Carcinoma
Negative for neuroendocrine markers, including parathyroid hormone
DIAGNOSTIC CHECKLIST
Clinically Relevant Pathologic Features
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