This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: AIIMS 2018, Subject name: Orthopaedics
10 year old present with ankle pain. X-ray has Lytic Lesion with sclerotic rim at calcaneum. Following HPE findings were seen. What is your diagnosis: 
Select and explain. 
A. Eumycosis, B. PVNS, C. Ochronosis, D. Hemophilic pseudotumar
D: Hemophilic pseudotumar
Answer: D: Hemophilic pseudotumar 
Explanation: X-ray shows multiple lytic lesion. Histopathology shows cells with brown-color deposits, hemosiderin. * Ochronosis: Usually presents with blackening of urine.* Pigmented villo-nodular synovitis (PVNS): is an aggressive disorder arising from synol joints predominantly in the knee. It shows area of synol proliferation with histology showing hemosiderin stained giant cells.* Eumycosis: Commonly found in foot. Presents with sinuses. It shows Dot in circle sign. X-rays shows multiple bone cavities and progressive bone destruction.* Hemophilic pseudotumor: Usually found in ankle joint. Histopathology shows hemosiderin deposit due to haemorrhage.