case_images: PMC11830221_01
case_images: Right eye-predominant proptosis.
case_images: cureus-0017-00000077580-i01.jpg
case_images: PMC11830221_01_cureus-0017-00000077580-i01.jpg
case_images: FIG1
case_images: An eight-year-old boy with no significant past medical history was brought to the outpatient clinic with a one-month history of bilateral proptosis, predominantly affecting the right eye (Figure 1), as the only finding on the physical exam.
case_images: MRI in T1 phase with contrast showing an expansive right retroocular lesion (red arrow).
case_images: cureus-0017-00000077580-i02.jpg
case_images: PMC11830221_01_cureus-0017-00000077580-i02.jpg
case_images: FIG2
case_images: An MRI confirmed the presence of an expansive iso-enhancing retroocular lesion that compressed the eye (Figure 2).
case_images: Numerous cells with a high nucleus-to-cytoplasmic ratio, prominent nucleolus, and mitotic figures.
case_images: cureus-0017-00000077580-i03.jpg
case_images: PMC11830221_01_cureus-0017-00000077580-i03.jpg
case_images: FIG3
case_images: The cells were arranged diffusely, occasionally with perivascular distribution (Figure 3).
case_images: Immunohistochemical stains demonstrating positivity for (A) CD34, (B) CD117, and (C) MPO.. MPO: myeloperoxidase.
case_images: cureus-0017-00000077580-i04.jpg
case_images: PMC11830221_01_cureus-0017-00000077580-i04.jpg
case_images: FIG4
case_images: Immunohistochemically, the tumor cells were positive for CD34, CD117, and myeloperoxidase (MPO) and focally positive for CD15 (Figure 4).
case_images: Flow cytometry showing a population of cells with high expression of MPO and CD34, while expressing relatively low CD3 and CD19, confirming their identity as myeloid blasts (red).. MPO: myeloperoxidase.
case_images: cureus-0017-00000077580-i05.jpg
case_images: PMC11830221_01_cureus-0017-00000077580-i05.jpg
case_images: FIG5
case_images: Flow cytometry revealed 57% myeloid blasts (CD45+(weak), CD34+, CD117-, CD64-, CD33+, CD13+) that lacked highly specific markers for lymphoid lineage (cyCD3-, CD19-, cyCD79a-, CD22-, CD7-, CD10-) but showed maturation into the neutrophilic lineage (cMPO++, CD45+, CD117-, CD33+, CD64-, CD36-, CD16-, IREM 2-) (Figure 5).