Familial pheochromocytomas and paragangliomas: stories from the sign-out room

A pathologist's view: molecular profiles for diagnosing pheochromocytomas and paragangliomas

Pheochromocytomas (PCC) and paragangliomas (PGL) are catecholamine (CA)-producing tumors classified into well (WD)-, moderately (MD)- or poorly differentiated (PD) types by the Grading of Adrenal Pheochromocytoma and Paraganglioma (GAPP). Seventy percent of PCCs/PGLs are WD type with 4% metastasis, the rest are MD with 60% and PD are with 88% metastasis. Thus, PCCs/PGLs can also be classified as low-grade (WD type), intermediate grade (MD type) and high-grade malignancies (PD types). MD/PD types are with 70% metastasis. Thus, PCCs/PGLs can also be classified as low-grade (WD type) and high-grade malignancies (MD/PD types) using GAPP. Hereditary PCCs/PGLs have been previously classified into cluster 1 or cluster 2 based on genetic mutations involved and types of catecholamine produced by the tumors. GAPP revealed that tumors in cluster 1 and cluster 2 correspond to MD type and WD type, respectively. Susceptible genes for high-grade malignancy (PD type) are currently unknown.

Recurrent paraganglioma of Meckel's cave: Case report and a review of anatomic origin of paragangliomas

BACKGROUND

Paragangliomas are rare, usually benign tumors of neural crest origin. They account for only 0.6% of all head and neck tumors. In the craniocervical area, they are more common in the carotid body and tympanico-jugular regions. To the authors' knowledge, a case of paraganglioma in Meckel's cave has not yet been reported in the medical literature. The pathogenesis and natural history of paragangliomas are still not well understood. We present a case of recurrent paraganglioma in Meckel's cave.

CASE DESCRIPTION

A 53-year-old woman was diagnosed with trigeminal neuralgia, dysesthesia and hypoesthesia on the left side of the face, hearing disturbance and a history of chronic, persistent temporal headaches. Magnetic resonance imaging (MRI) showed a lesion located in Meckel's cave on the left side, extending to the posterior cranial fossa and compressing the left cerebral peduncle. The lesion was first thought to be a recurrence of an atypical meningioma, as the pathologist described it in the tissue specimen resected 3 years earlier, and a decision for re-operation was made. A lateral suboccipital approach to the lesion was used under neuronavigational guidance. The tumor was removed, and histological examination proved the lesion to be a paraganglioma. Five months later, the follow-up MRI showed local regrowth, which required subsequent surgical intervention.

CONCLUSIONS

A paraganglioma in Meckel's cave is an uncommon tumor in this location. Although ectopic paragangliomas have been described in the literature, a paraganglioma atypically located in Meckel's cave makes a topographic correlation difficult, mainly because paraganglionic cells are usually not found in Meckel's cave. Another peculiarity of the case is the local recurrence of the tumor in a relatively short time despite an attempted, almost gross total resection.

Stathmin expression in pheochromocytomas, paragangliomas, and in other endocrine tumors

Pheochromocytomas are neuroendocrine tumors confined to the adrenal glands, and malignant pheochromocytomas can spread to various sites including the liver, lung, and bones. Paragangliomas occur in numerous locations in the body, so assessment of metastatic disease is more challenging, as patients with familial syndromes often have multiple, possibly independent paragangliomas. The most reliable criterion for malignancy in pheochromocytomas and paragangliomas is metastatic disease. Because there are few immunohistochemical markers that are useful in the diagnosis of malignancy in pheochromocytomas and paragangliomas before they metastasize, more markers are needed to characterize these tumors. Stathmin is a widely expressed 17-kDa cytoplasmic, microtubule destabilizing and sequestering phosphoprotein that is important in cell motility and cancer cell metastasis. It is upregulated in various malignancies. We examined stathmin expression in tissues from patients with pheochromocytomas (n = 48), malignant pheochromocytomas (n = 28), paragangliomas (n = 42), and malignant paragangliomas (n = 21) by immunohistochemistry using tissue microarrays (TMA) with a polyclonal antibody against stathmin. A series of other endocrine tissues and tumors (n = 70) were also examined for stathmin expression. Stathmin was more highly expressed in pheochromocytomas compared to normal adrenals, a finding confirmed by Western blot. There was higher expression of stathmin by immunohistochemical staining in malignant pheochromocytomas compared to pheochromocytomas without metastasis when analyzed by maximal staining (p = 0.012). Stathmin was present in a wide variety of endocrine tumors and was most highly expressed in rapidly proliferating tumors including anaplastic thyroid carcinomas, Merkel cell carcinomas of the skin and small cell carcinomas of the lung. These results show that stathmin is expressed at higher levels in more rapidly proliferating endocrine tumors. However, it is probably not useful as a stand-alone marker to determine malignancy in pheochromocytomas for individual tumors.