The Histopathologoid

( This is another final part of the Sabah lymphoma talk: Part One , Two , Three . ) I. Marginal zone B cell lymphoma Types: Nodal, extranodal, splenic. Immunohistochemically different from mantle cell lymphoma, follicular lymphoma, and small lymphocytic lymphoma. Differential diagnosis: Reactive monocytoid B-cell hyperplasia. Patterns: Diffuse pattern: diffuse sheets of neoplastic cells with effacement of nodal architecture. Nodular pattern: distinct nodules, well-demarcated. Interfollicular pattern: neoplastic cells in interfollicular areas that surround residual germinal centres. Perifollicular pattern: annular distribution of neoplastic cells around the uninvolved normal secondary follicles. Histology: Vague nodules with sclerosed blood vessels. Stromal sclerosis which compartmentalize the small groups of neoplastic cells. Monocytoid / plasmacytoid cells, singly distributed or in clusters. Increased large cells with nuclear pleomorphism (not seen in mantle cell l...

( This is another continuation of the Sabah Lymphoma talk -- first and second part ) I. Toxoplasma Three features: Follicular hyperplasia. Epithelioid histiocytes. Monocytoid B cells in sinusoids. Enlarged germinal centre (still have mantle zone and tingible body macrophages) II. Viral Partial architectural effacement with expanded paracortex. Polymorphous cellularity. Mottled histological appearance with marked follicular hyperplasia. Infectious mononucleosis Expanded paracortez with heterogenous population. Increased blood vessels. Presence of immunoblasts that mimic Reed-Sternberg cells. Hyperplastic follicles. Herpes simplex virus Mixed cell population. Reed-Sternberg-;ole activated lymphocytes. Apoptotic cells and neutrophils. HIV Early: present with acute reactive lymphadenitis. Late: present with marked CD4+ T-cell depletion, and involution of lymph nodes. 3 phases: Acute Non-specific, more to viral lymphadenitis, eg paracortical exp...

(This is a continuation of the notes I have taken from the Sabah Lymphoma talk ) I. Lymphadenopathies Lymphadenopathies are divided into three: 1. Reactive lymphoid hyperplasia 2. Atypical lymphoid hyperplasia 3. Progressive transformation of germinal centre 1. Reactive lymphoid hyperplasia Has a follicular pattern OR may present as diffuse paracortical hyperplasia. Characteristics: architecture preserved, capsule intact, enlarged germinal centre, mitotically active, tingible body macrophages, mantle zone present . Main differential of follicular pattern: follicular lymphoma. 2.  Progressive transformation of germinal centre Mainly in adolescent males. Numerous follicules in different stages with follicular hyperplasia. Late stage: small lymphocytes infiltrating germinal centres, germinal centre disrupted. II. Castleman's disease 1.  Hyaline vascular variant Can be unilocular or multiple places. Numerous follicles with small germinal centre, on...