Unicentric mixed variant Castleman disease associated with intrabronchial plasmacytoma

VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/2872096831190851. Castleman disease (CD), described as a heterogeneous lymphoproliferative disorder, can be divided into different subtypes according to clinical appearance (unicentric and multicentric form) and histopathological features (hyaline vascular, plasma cell, mixed type, human herpesvirus 8–associated and multicentric not otherwise specified). Unicentric CD is known to be usually of the hyaline vascular variant, plasma cell and mixed type of this form are quite uncommon. Malignancies are mainly associated with the multicentric form. We report a rare case of unicentric mixed variant CD evolving into intrabronchial, extramedullary plasmacytoma. Intrabronchial mass with consequential obstruction of the left main bronchus, left lung atelectasis and mediastinal lymphadenomegaly was detected by chest CT in our patient suffering from cough and hemoptysis. Pulmonectomy was performed, histopathological and immunhistochemical analysis of lymph nodes revealed mixed type of CD with interfollicular monotypic plasma cell proliferation. The intrabronchial mass consisted of monotypic plasma cells confirming plasmacytoma. Systemic involvement was not confirmed by further tests. Although malignancies more often present in multicentric CD that usually belongs to the plasma cell subtype, this case confirms the neoplastic potential of the rarest, unicentric mixed variant of CD.