In this report, we describe a case of unicentric Castleman disease that presented as an indolent mass of the neck, pathologically confirmed as hyaline vascular type after surgical excision.
Castleman’s disease was first described in 1956 by Castleman and his colleagues [1]. It is a rare benign condition of the lymph nodes, also known as angiofollicular or benign giant lymph node hyperplasia. The aetiology of this lymphoproliferative disease remains poorly understood, but the current consensus is that there is a wide range of clinical entities within this disease [2].
Unicentric disease is the most common type and it usually presents as an asymptomatic solitary mass, with the most common variant being the microscopic hyaline vascular, which can be surgically treated with success. On the contrary, the multicentric type has a broader histologic range and is usually more aggressive. Of these, the human herpes virus-8 (HHB8)-associated Castleman disease, which occurs in immunosuppressed patients, is the only type in which a specific pathogenic agent is known to cause the disease [2]. The remaining multicentric cases that do not have a specific pathogenic agent are considered in the broad category of idiopathic multicentric Castleman’s disease (HHV8-negative disease) [3]. These cases are rare but life-threatening, and specific diagnostic criteria have been established to facilitate this particularly challenging diagnosis [4].
Even though it is a disease of the lymph nodes which can theoretically affect any nodal chains, unicentric disease has a predilection for the mediastinal nodal chains. Nevertheless, because of its clinical variability and the ability to potentially affect any body region (including the neck, abdomen and pelvis), this disease frequently represents a diagnostic challenge [5].
On imaging studies, unicentric disease usually presents as a well-defined mass that displaces surrounding structures. Because of their high vascularity, these lesions show intense enhancement after contrast administration on both CT or MRI, and intralesional flow voids may be seen on T1- and T2-weighted images [6]. Their location and signal characteristics usually prompt differential diagnosis with neurogenic tumours which are also highly vascular, including paragangliomas and pheochromocytomas, as well as sarcomas or lymphomas. Other rare diagnosis such as ectopic cervical thymoma should also be kept in mind [7]. PET/CT is able to detect increased metabolic activity in the affected lymph nodes, even if their size is normal, and it is a helpful tool for an accurate staging and monitoring of the disease. Nevertheless, excisional biopsy remains the method of choice for diagnostic confirmation [8].
Unlike multicentric disease, this type usually has an excellent outcome after curative surgical treatment, which was the case for our patient.
Take-Home Message: Unicentric Castleman disease is a rare benign disease which should be considered in the differential diagnosis of hypervascular lesions located in the topography of many nodal chains, including the neck. Unlike its multicentric counterpart, unicentric disease is usually associated with the hyaline vascular type and shows an indolent and benign clinical course, with very good outcome after surgical excision, which is needed for the definite diagnosis.
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