Endosonographic features of unicentric Castleman Disease

BACKGROUND: Castleman disease (CD) is a rare lymphoproliferative disorder most frequently occurring in the mediastinum. Peripancreatic forms are less frequent. Few cases of endoscopic ultrasonography-fine-needle aspiration (EUS-FNA) findings of this lesion have been reported, where no real-time tissue elastography (RTTE) has been described in the literature to our knowledge. METHODS: We describe the endosonographic, elastographic, cytologic and immunocytochemistry findings in two cases of unicentric CD of the hyaline vascular variant. RESULTS: Two females, aged 41 and 34 year were referred to our hospital for further EUS evaluation of a peripancreatic mass found incidentally on computed tomography. EUS examination revealed around, well-demarcated, uniformly hypoechoic mass measuring 52 and 23 mm respectively, with smaller adjacent hypoechoic lymph nodes. Doppler examination revealed intense peripheral vascularity, together with prominent penetrating feeding vessels entering a distinct hilum. RTTE revealed a relatively homogenous soft elastographic pattern. EUS-FNA provided smears with clusters of lymphocytes in a hemorrhagic background. Cell block preparation showed immature lymphocytes surrounding lymphocyte-poor centers with vascular proliferation. Immunohistochemical staining of the cell block sections showed CD45-leukocyte common antigen, CD20, CD23, CD79a, Bcl-2 and CD5 positivity in small lymphocytes. Cytology was suggestive of non-Hodgkin's lymphoma. Surgical excision was performed in both cases and histopathology was consistent with CD of the hyaline vascular type. CONCLUSION: The echo features of a solitary hypoechoic homogenous well-demarcated mass with prominent vasculature and increased elasticity should raise the possibility of unicentric CD. EUS-FNA usually cannot make a definitive distinction from certain kinds of lymphoma.