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Low grade lymphoma

( 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...

Infective Conditions of the Lymph Node (Lymphadenitis)

( 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...

Reactive Conditions of the Lymph Node

(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...

Autopsy exam

Autopsy exam is a necessity for a trainee anatomic pathologist to pass the final exam, but it is quite a pain to study for it.  I found some brief notes (and possible exam questions) to survive the exam. Assessment: History Gross findings Dissect all organs Make sure dissection area is clean. Cause of death and correlation. How does one diagnose pneumothorax on autopsy? Dissect out the circle of Willis. How to measure ventricular thickness. Answer: 1 cm below the atrioventricular valve How to differentiate between kidney abscess and pyonephrosis. Kidney abscess is usually located at the renal cortex. How to take swabs (from any sites) How to take blood samples. Answer: from femoral vein or right atrium. How to take urine sample. Answer: suprapubic Spleen may also show hyaline arteriosclerosis, like kidneys (hypertensive change). Renal papillary necrosis is common in diabetes mellitus. ARDS (adult respiratory distress syndrome) is a manifestation of ...

Melanocytic lesions potpourri

Lentigo maligna Basically, lentigo maligna has increase in melanocytes.  Morphologically, melanocytes has cytoplasmic halo while basal cells do not have halo.  However, melanocytes may pass melanin to basal cells, causing confusion.  Therefore to disprove lentigo maligna, one has to do S100 IHC stain. Junctional and compound naevus DO NOT DIAGNOSE IN ADULTS, therefore treat with suspicion. The differential here will be superficial melanoma or melanoma in situ.

Giant cell tumour of bone (vs aneurysmal cyst)

In giant cell tumour of bone, what we will see is: 1. Multiple numerous nuclei within cell  with ill-defined border (in other words, multinucleated cell)      usually more than 10 nuclei; usually 50-100 nuclei 2. Mixture of multinucleated cells with neoplastic mononuclear cells 3. Mitosis rarely seen, with no atypical forms seen. Whereas for aneurysmal bone cyst (a potential differential diagnosis), what we will see is: Lumen containing blood surrounded by bone and collagen.

Hodgkin lymphoma

Hodgkin lymphoma Useful stains are: CD3 CD20 CD15 CD30 PAX5 (fainter than reactive B cells; membrane staining) Hodgkin lymphoma vs anaplastic large cell lymphoma (ALCL) Hodgkin lymphoma: Scattered large cells. ALCL: More clustered formation, mixture of small and large cells.

Introduction to Lymph Node

I have found a note that I have made during a lymphoma talk at Sabah by Dr Ahmad Toha.  Here is the gist of it. About Lymphoid Follicles There are two types of lymphoid follicles: one is primary and another is secondary lymphoid follicle. Primary lymphoid follicle: dark blue in colour, stain less with Ki-67 proliferative index marker. Secondary lymphoid follicle: has paler areas, stain more with Ki-67 proliferative index marker. Useful markers for lymph nodes: CD20: germinal centre and mantle cell. CD79a: stronger staining at the mantle zone. BCL-2: an anti-apoptotic marker, mostly stain outside the follicle with 'sprinkle' of positive cells inside the follicle.  These positive cells inside the follicles are T-helper cells. CD21: identify the nodular appearance of the follicles. Ki-67 BCL-6: germinal centre CD10: germinal centre IgD: stain outside the germinal centre (?mantle zone) About Thymus: 1. Paracortex Densely cellular Located beneath cortex, at c...

Pearls of wisdom from Professor Dr Tan Puay Hoon

We had some interesting cases shown to Prof Dr Tan PH from SGH, and received a nice tutorial from her in return :). 1. Papillary lesion In a papillary lesion, one should use more than one myoepithelial marker.  The myoepithelial markers potpourri: p63, HMWCK (either CK 5/6 or CK14), SMA. Pitfall in papillary lesion: secretory cells may have aberrant p63 expression. Neoplastic (and suspicious) papillary lesion will exhibit clonal proliferation.  ER is preferably used: diffuse positivity will suggest clonal proliferation, whereas intraductal papillomas will usually exhibit patchy ER positivity.  PR may be used in conjunction with ER but the staining is more heterogeneous, therefore it may be confusing to identify clonal proliferation by using PR immunohistochemical stain. HER-2 immunohistochemical stain is used only if there is invasive disease, and not really used to establish clonality. Encapsulated papillary carcinoma is more expansile and bulging compared to...

8 L's and DRUGS

I am so happy that I found an educational gem by Sullivan Nicolaides Pathology , a private pathology lab in Australia.  There are some videos of live lectures that one can find here.  I am particularly excited (and maybe starstruck) to find Professor  David Weedon's lectures here -- as I am particularly fond for Dermatopathology. A particular thing I learned today from Professor David Weedon was a checklist mnemonic for perivascular infiltrate in the skin: 8L's and DRUGS Light reaction Lymphoma (and pseudo) Leprosy Lues Lichen striatus Lupus erythematosus Lipoidica (and incomplete granuloma annulare) Lepidoptera (arthropods etc) Dermatophyte Reticular erthymatous mucinosis Urticaria Gyrate erythema Scleroderma