Paragangliomas malignant

FIGURE 11.17 Relative reactivity patterns for neuroendocrine carcinoma (NEC) and malignant paraganglioma (PARAGNG) of the mediastinum. 

Odze R, Begin LR. Malignant paraganglioma of the posterior mediastinum. Cancer. 1990 65 564-569. 

In addition to catecholamines, serotonin immunoreactivity has been demonstrated in approximately 80% of pheochromocytomas. Both pheochromocytomas and extra-adrenal paragangliomas may also contain peptide hormones including neuropeptide Y (64%), substance P (36%), calcitonin (21%), and leu- and met-enkephalin (70%). 475 Several studies have indicated that determination of circulating levels of neuropeptide Y may be useful in the diagnosis and monitoring of patients with these tumors. Helman and coworkers demonstrated that neuropeptide Y mRNA is present in all benign pheochromocytomas but in only 30% of malignant pheochromocytomas. 

Parathyroid carcinoma (PAC) may be seen intrathymically or in the soft tissue of the anterosuperior mediastinum. It bears a considerable resemblance to thymic neuroendocrine carcinoma in some cases, and paraganglioma also enters into differential diagnosis.The clinical diagnosis of malignant parathyroid lesions is typically... 

FIGURE 11.24 Labeling of sustentacular cells for S-100 protein (A) and chromogranin A (B) in mediastinal paraganglioma (C). S-1 00 protein tends to be lost when tumors of this type acquire overtly malignant biological properties. 

Plaza JA, Wakely Jr PE, Moran G, et al. Sclerosing paraganglioma Report of 19 cases of an unusual variant of neuroendocrine tumor that may be mistaken for an aggressive malignant neoplasm. Am J Surg Pathol. 2006 30 7-12. 

In contrast to metastatic carcinoma, MXPEs lack malignant cytology, have a lower MIBl LI, and are locally fibrillar. Paragangliomas may mimic MXPEs, but MXPEs lack chromogranin A and express GFAP. 

Protein gene product 9.5 Malignant nerve sheet tumor, paraganglioma Carcinoid tumors Neurons and nerve fibers, neuroendocrine cells, renal tubular epithelium, spermatogonia, Leydig cells... 

The malignant potential of paraganglioma is reported as between 10% and 18% on the vagal, carotid and laryngeal locations while in the temporal area is about 3%. Spontaneous regression of paragangliomas has never been reported. It usually has a slow growing rate but in some cases can be rapid or associated with additional tumors in other locations. 

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