Lytic lesion of the knee in a 27-year-old man

Isolated myeloid sarcoma of the tibia: A case report

INTRODUCTION

Myeloid sarcoma (MS) is a rare extramedullary tumor composed of malignant myeloid cells that most commonly arise in patients previously diagnosed with myeloproliferative disease. However, they can still occur in isolation and without bone marrow disease.

CASE PRESENTATION

An 8-year-old girl who had a history of acute myeloid leukemia and was off treatment for four years presented to the clinic with a history of on and off left knee swelling and pain without any direct trauma to the knee over the last two years. Knee Magnetic resonance imaging (MRI) showed diffused joint effusion with proximal tibia focal edema. A diagnosis of juvenile rheumatoid arthritis was suspected, and the patient was started on treatment, but the problem did not resolve. Eventually, the patient underwent a repeat MRI and showed increased joint effusion with an increase in the focal edema. An open bone biopsy of the lesion was taken, and the histopathology showed sheets of primitive mononuclear cells positive for CD33 and CD117 and negative for CD34, myeloperoxidase, CD10, CD20, and CD68, indicating myeloid sarcoma.

CLINICAL DISCUSSION

Histological examination and immunohistochemistry are the most important in diagnosing myeloid sarcoma. Previously, before the introduction of chemotherapy and stem cell transplant, such cases of proximal tibia MS were treated with surgical resection of the bone. However, chemotherapy with the possibility of an allogeneic hematopoietic stem cell transplant (alloHSCT) has changed the view of survival in such cases.

CONCLUSION

Isolated proximal tibia myeloid sarcoma is a rare occurrence that can be misdiagnosed and lead to delayed treatment. Bone biopsy, Immunohistochemistry, and cytogenetic studies play a critical role in differentiating MS from other types of tumors.

Nonleukemic granulocytic sarcoma of knee: a case report

Granulocytic sarcoma (GS) is a rare extramedullary tumor composed of immature myeloid cells. It is usually associated with leukemia or other myeloproliferative disorders. It occurs very rarely without overt hematologic diseases. A 19-year-old man presented with left knee mass. Biopsy with pathological analysis showed lymphoma aspect. Immunostains yielded the diagnosis of GS with myeloperoxidase and CD43 positivity. There was no systemic manifestation of leukemia, and bone marrow biopsiy was negative for neoplastic infiltration. Chemotherapy by CHOP was efficient, and the patient remaind alive and healthy 40 months after the end of treatment. The case is discussed in the framework of the existing literature about the diagnosis, treatment, and prognosis of this very rare condition.