Sclerosing Paraganglioma of the Carotid Body: A Potential Pitfall of Malignancy

Abstract

Paragangliomas (PGs) of the head and neck region are typically benign, slow-growing neuroendocrine tumours. At times, they may exhibit unusual histological features, such as prominent stromal sclerosis (sclerosing PG), which may raise concerns of malignancy. We describe a case of sclerosing PG of the carotid body, emphasizing the value of immunohistochemical stains for differential diagnosis. A 43-year-old woman presented with a painless lump on the neck. A magnetic resonance imaging scan demonstrated a hypervascular lesion of the carotid body, which was surgically excised. Grossly, the lesion measured 1.8 cm at maximum diameter. On microscopic examination, irregular nests and tiny bundles of neoplastic cells were found between thick bands of fibrous tissue. Focal nuclear cytomegaly and marked pleomorphism were noted. Neoplastic cells proved to be immunoreactive for chromogranin, synaptophysin and neuron specific enolase, but negative for cytokeratins, smooth muscle actin and CD34. Ultrastructurally, numerous mitochondria, rough endoplasmic reticulum structures and endocrine granules were seen in the cytoplasm of the tumour cells. On consideration of the above-mentioned clinico-pathological and ultrastructural findings a diagnosis of sclerosing PG was established. Sclerosing PG is a rare entity which may mimic a malignant neoplasm. The recognition of this unusual morphological variant of PG, together with appropriate immunostains, leads to the correct diagnosis.

Sclerosing Paragangliomas of the Carotid Body: A Series of a Rare Variant and Review of the Literature

“…2,7 Management is largely similar to conventional carotid body paragangliomas. Surgical resection is indicated because there is no clear histological differentiation between benign and malignant carotid body paragangliomas and even though most are benign, malignancy is encountered often.…”

“…Unusual variant morphology may also be present in the form of clear or spindle cell changes, diffuse growth, or mixed cell phenotypes. 7 The histopathologic criteria for predicting the biologic behavior of carotid body paragangliomas remain controversial. Although the presence of central necrosis, vascular or perineural invasion, and mitoses suggest malignant tumor behavior, evidence of metastasis is currently considered to be the only reliable criterion for establishment of malignancy.…”

“…These factors coupled with the lack of any reliable histological criteria for determining the biological activity and metastatic potential of carotid body paragangliomas can mean that this diagnostic pitfall may lead to an overdiagnosis of malignancy. 7 The sclerosing carotid body paragangliomas are rare and predominantly benign tumors 17 which can present a diagnostic challenge as they can often be confused for malignant tumors. 7 The correct diagnosis is of paramount importance as this directs subsequent clinical intervention.…”

“…7 The sclerosing carotid body paragangliomas are rare and predominantly benign tumors 17 which can present a diagnostic challenge as they can often be confused for malignant tumors. 7 The correct diagnosis is of paramount importance as this directs subsequent clinical intervention. Awareness of this particular histological subtype can prevent misdiagnosis of malignancy as well as avoid unnecessary intervention and emotional stress to the patient.…”

Paraganglioma of the Carotid Glomus

“…In microscopy The microscopic architecture is made up of small cord-shaped units consisting of 10 to 20 polygonal cells, separated by a reticulinic network and surrounded by a highly vascularized stroma [9,23]. In immunohistochemistry, the main cells express general neuroendocrine markers, such as NSE (enolase specific neuron).…”