The Histopathologoid

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.

Venous congestion is a feature of acute inflammation rather than chronic inflammation. HMWCK (CK5/6) will stain more for carcinoma if LMWCK (for example, CK MNF 116) unable to pick up for the carcinoma.

Foamy macrophages may be seen in FSGS (focal segmental glomerulosclerosis)

What clinical information is important in medical renal biopsy? Renal profile UFEME Antibody screen Urine protein or protein-creatinine index (PCI) Glomerular count

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.

1. MPO (myeloperoxidase) 2. CD117 3. Glycophorin 4. CD34

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.