Diagnosis: Cryptosporidiosis (Cryptosporidium spp.) 4-6 mm oocysts Intracellular but extracytoplasmic localization (within enterocytes but at the luminal surface). H&E stain appearance: Basophilic oocysts lining the epithelium. Confirmatory Tests: ✅ Acid-fast staining (Modified Ziehl-Neelsen stain) → Red-staining oocysts. ✅ Immunofluorescence assay (IFA) or Direct Fluorescent Antibody (DFA) test → High sensitivity and specificity. ✅ PCR-based detection → Molecular confirmation in stool samples. 📲https://youtu.be/9Jg5r0k4l1A?si=xYUSERbgIb2_lEyW ➡️https://pathologymcq.com/differentiating-common-protozoan-infections-in-the-gi-tract-a-histopathological-perspective/ Reference: Odze and goldblum Gastrointestinal Pathology - 5th edition.