( J ) Negative BCL2 immunostain is a follicular lymphoma marker; thus, the negative staining rules out follicular lymphoma in this lesion. described by Castleman et al in 1954 in a group of patients with localized lymph node hyperplasia. 2 3 The etiology of CD remains largely unknown; the pathogenesis show inflammatory response to a mysterious antigenic stimulus with chemical mediators (cytokines) of inflammation particularly interleukin-6 (IL6) playing a prominent role. 1 2 CD can be categorized histomorphologically into three distinct subtypes, namely: hyaline vascular, plasma cell, and mixed hyaline vascular plasma cell types. 1 2 4 5 6 7 8 CD also has two clinicopathological presentations, namely: unicentric Castleman disease (UCD) and multicentric Castleman disease (MCD) forms, wherein the unicentric forms are more common. 1 2 5 6 8 The UCD form presents as a solitary (unifocal) lymph node lesion especially in the mediastinum and less commonly in extrathoracic sites and may not be accompanied by systemic symptoms such as fever, night sweats, fatigue, weight loss, splenomegaly, anemia, and hypergammaglobulinaemia. 1 2 5 6 8 The MCD form, on the other hand, presents as a multifocal Ramelteon (TAK-375) lymph node lesion with generalized lymphadenopathy, especially in the neck region, associated with more aggressive systemic symptoms such as fever, night sweats, fatigue, cachexia, splenomegaly, cytopenia, and hypoglobulinemia/hyperglobulinemia, hence resembling a malignant (Hodgkins) lymphoma. 1 2 5 6 8 Furthermore, this MCD form can be subcategorized into three subtypes, namely: human herpes virus-8 associated MCD (HHV8-MCD), polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder, skin changes-associated MCD (POEMS-MCD), and idiopathic MCD (iMCD). 2 6 8 9 Additionally, iMCD is further subdivided into two types, namely: iMCD associated with thrombocytopenia, anasarca, fever, reticulin myelofibrosis and renal dysfunction and organomegaly (iMCD-TAFRO) and Ramelteon (TAK-375) iMCD not associated with TAFRO hence not otherwise Ramelteon (TAK-375) specified (iMCD-NOS). 2 8 It is also noted that Goat polyclonal to IgG (H+L) nonidiopathic MCDs occur in the background of human immunodeficiency virus (HIV) infection especially in association with Kaposi sarcoma herpesvirus (KSHV) or HHV8 as well as in association with secondary amyloidosis. 1 2 6 8 10 Ramelteon (TAK-375) Histomorphologically CD is distinct from malignant lymphoma; however, these two lesions can coexist or even, indeed, mimic each other like in this case report. 1 6 11 12 13 14 15 16 17 18 In such scenarios, immunohistochemical (IHC) evaluation of the lymph node specimen in addition to routine H&E histopathological evaluation becomes the gold standard in arriving at a definitive diagnosis. 1 5 11 13 14 15 19 This case is reported because of its rarity and thus should be considered in the differential diagnosis of generalized lymphadenopathy, and also to show how important IHC is in resolving diagnostic dilemmas in lymph node pathology. Case Report The patient is a 68-year-old woman who presented with a 1-year history of abdominal swelling and pain. These symptoms were of gradual onset and progressive over time. There was history of constitutional symptoms including low grade fever, night sweat, and weight loss. There was also a history of easy fatigue and mild unproductive cough. Clinical examination revealed moderate to severe pallor, bilateral axillary lymphadenopathy. Abdomen was mildly distended and tender with splenomegaly of approximately 14 cm and liver was tipped. Other systems examined were unremarkable. Routine laboratory investigations such as full blood count showed normocytic normochromic anemia with hemoglobin level of 7.0 g/dL; renal and liver function test and other biochemical tests were normal. HIV serology was nonreactive. Abdominal ultrasound scan showed massive splenomegaly. Computerized tomography of the abdomen revealed minimally enhancing solid presacral soft tissue mass with solitary metastasis to the spleen and lumber vertebrae suggestive of lymphoma. Bone marrow aspiration showed feature of nutritional anemia and small lymphoid follicular aggregates. Excision biopsy of both axillary lymph nodes was performed Ramelteon (TAK-375) and subjected to routine histopathological and IHC evaluations. Routine histopathological evaluation revealed complete effacement of normal lymph node architecture by polymorphous population of cells comprising mainly lymphocytes, plasma cells, and macrophages which were intimately admixed with cells having vague Hodgkin-Reed-Sternberg lacuna cell appearance. The background of this lesion was largely.