The most likely diagnosis is
This is a typical presentation of stage IV neuroblastoma, with the primary tumor arising from orie of the paravertebral sympathetic ganglia and metastasizing to bone marrow, cortical bone, and the retro orbital tissues. Histiocytosis X may have a somewhat similar presentation and involve multiple bones, but it usually involves one rather than both orbits; the right flank mass and tumor clumps in the marrow of this patient also are not characteristic" of histiocytosis X. Rhabdomyosarcoma may arise in the orbit but usually is unilateral; the tumor also rarely is associated with systemic metastases at initial diagnosis. Wilms tumor would produce a right renal rather than suprarenal mass and would metastasize to the lungs rather than to bone and bone marrow. Lymphoblastic lymphoma usually arises in the anterior mediastinum or peripheral node's. Even if it were to present with widespread dissemination, abdominal rather than thoracic disease would be unusual and Lymphoblasts rather than tumor clumps would be seen in the marrow.
Histiocytosis X
Rhabdomyosarcoma
Neuroblastoma
Wilms tumor