Renal Transplant Rejection – v3 lesion with transmural inflammatory cell infiltrate. Denotes Banff III acute cell mediated rejection. #RenalPath @ziad_zaatari

28 year old male who p/w severe headaches and expired 2 months later. Autopsy revealed an infiltrating mass arising near the 4th ventricle with bizarre giant and profoundly pleomorphic cells. This is a diffuse midline glioma, H3 K27M - mutant @drmarmolani @NedaWickEdPath

Synovial sarcoma of the parotid gland is very rare and comprises only 0.3-1.5% of the primary tumors of the parotid gland. The diagnosis is confirmed by FISH studies which is positive for SSX-SYT;T(X:18) @HansiniMD

Benign cardiac tumor composed of fetal cardiac myoblasts. Most arise within setting of tuberous sclerosis complex. Sheets of large polygonal cells with large, clear vacuoles. Some cells have eosinophilic cytoplasm that is retracted away from cell membrane ("spider cells"),

Fibrillary Glomerulonephritis – Mesangial expansion by weak PAS-positive material, congo red negative. IF shows mesangial and capillary loop IgG deposits. EM with randomly arranged, non-branching fibrillary deposits. #RenalPath @ziad_zaatari

Renal Amyloidosis – Congo red stain showing classic “apple green” amyloid deposits (here, in a vessel wall) under polarized light. #RenalPath @ziad_zaatari

Epithelioid predominant Wilms Tumor. Malignant embryonal neoplasm derived from nephrogenic blastema cells, typically showing multiphasic patterns of differentiation.

Anaplastic Sarcoma of the Kidney with DICER1 mutation from a female child. DICER1 mutations are also seen with pleuropulmonary blastoma, multinodular goiter, PTC, cystic nephroma, Wilms’ tumor, ovarian tumors, and embryonal rhabdomyosarcoma. #pathology #pedipath @sarah_glogowski

Polymorphous low-grade neuroepithelial tumor of the young (PLNTY). Infiltrative growth patterns. Strong CD34 immunopositivity in the axons. Nearly all harbor BRAF V600E mutations or fusion events involving FGFR2/FGFR3. #pathology #pedipath @sarah_glogowski

Placental site trophoblastic tumor. Persistently elevated hCG post delivery. Endometrial implantation. Sheets of polygonal to spindle intermediate trophoblastic cells with atypical, irregular, hyperchromatic nuclei, and eosinophilic cytoplasm. #pathology #gynpath @sarah_glogowski

Complete Hydatidiform Mole. Hydropic villi. No embryonic tissue present. p57 negative. Very high hCG. Uterus large for dates. Bunch of grapes on gross exam. #pathology #PlacentalPathology @sarah_glogowski

Leiomyomatous Hamartoma. Slow growing polypoid mass removed from the palate of a female infant. #pathology #pedipath @sarah_glogowski

Rhabdomyosarcoma. Primitive malignant tumor of rhabdomyoblasts. Tumor cells have eccentric round nucleus with bright eosinophilic cytoplasm. #1 most common soft tissue malignancy of childhood/adolescence. #NKcell_MD

Giant cell tumor of bone. Tumor of the mononuclear preosteoblasts (neoplastic) which express RANK ligand that attracts osteoclast-like giant cells (not neoplastic) with RANK receptor. H3F3A histone gene driver mutation. #NKcell_MD