Teaching Case

A 28-year-old patient presented with right pre-auricular swelling for one year with the gradual increase in size since 2 months associated with generalised weakness and malaise. There was no history of trauma or suspicious lesions elsewhere in the body

Ultrasound imaging reveals multiple well-circumscribed hypoechoic lesions with mild posterior acoustic enhancement and heterogeneous solid components within showing internal vascularity are noted within the superficial lobe of the right parotid gland. MRI revealed a few enlarged ovoid lesions showing T1 hypointense signal, T2 isointense with diffusion restriction on DWI. In post-contrast study, there is diffuse homogeneous enhancement with few non-enhancing T2W hyperintense areas. On imaging, the parotid mass was labelled as Warthin’s tumour.

Angiofollicular lymph node hyperplasia (Castleman’s disease) is a benign lymphoproliferative disorder affecting the lymph nodes of young adults. The likely etiological factors include Lymphoid-hamartomatous hyperplasia, immunodeficiency, chronic low-grade inflammation or autoimmune phenomena.[3] Pathologically, hyaline vascular Castleman’s disease is characterized by atretic germinal centers , thickened mantle zones with lymphocytes arranged in layers forming onion skin-like appearance. There is prominent vascular proliferation with hyalinization of the vessel walls.[2,5] The disease can affect any lymph node in the body, with the mediastinum being the most commonly involved site[1,2]. The disease entity affecting the head and neck is rare with extremely rare chances of involvement of the salivary glands. The disease may present as unicentric or multicentric forms, the unicentric form of the disease is usually asymptomatic, whereas the multicentric form usually presents as generalized lymphadenopathy, hepatosplenomegaly, and follows an aggressive clinical course [7]. Imaging plays an important role in differentiating the two forms of the disease, which have considerable differences in presentation, treatment, and prognosis. Castleman’s Disease of the head and neck, especially parotid is often a diagnostic challenge because it mimics other neoplasms and presents itself with very few symptoms and signs. Ultrasonography helps to evaluate the vascular nature of the disease. Contrast-enhanced Computed tomography scan will show well defined homogeneously enhancing mass with speckles of calcification, reflecting the hypervascular nature of the lesion. On magnetic resonance imaging, Castleman’s disease shows hyper to isointense signal, especially on T2- weighted sequences with uniform post-contrast enhancement. However, the definitive diagnosis is only possible with histopathological examination.[4] In this case, FNAC and biopsy proved to be unicentric Castleman's disease.

Total excision of the mass forms the basis of treatment for the unicentric type with no recurrence. However, the non-operable cases and multicentric form of disease are controlled by palliative treatment with radiotherapy, corticosteroids, and chemotherapy. Unicentric Castleman’s disease of parotid mimics parotid neoplasms, hence considering it as a differential diagnosis becomes crucial in early detection of the multicentric form. Timely screening of the abdomen and thorax can rule out a multicentric form of the disease which has a poorer clinical outcome and different treatment modalities. In this case, screening of the abdomen and thorax revealed no lymphadenopathy or mediastinal mass, suggesting unicentric Castleman’s disease of the parotid.