Extramedullary Acute Myeloid Leukemia: Testicular Myeloid Leukemia, Leukemia Cutis with Leptomeningeal Involvement
Authors: Saeed Zabila 
Published: November 2021

Abstract
Extramedullary Acute Myeloid Leukemia: Testicular myeloid leukemia, leukemia cutis with leptomeningeal involvement
Z Saeed, H Aslam, A Weil, M Muzaffar
Myeloid sarcoma also called granulocytic sarcoma, myeloblastoma, or chloroma is an extramedullary tumor of immature granulocytic cells. Extramedullary soft tissue manifestations are relatively rare in hematological malignancies. One of the rarest manifestations is myeloid sarcoma (MS). MS develops as part of acute myeloid leukemia, myeloproliferative neoplasm, or myelodysplastic syndrome or at relapse, especially following allogeneic hematopoietic stem cell transplant. Demographically, it has a slight male predominance with a male to female ratio of 1.2: 1. It may occur at any age and any site in the body leading to varied clinical presentations. The most reported sites are lymph nodes, skin and soft tissues, bone, testes, gastrointestinal tract, and peritoneum.
44 year old male with past medical history of diabetes mellitus type 2 and morbid obesity presented with right testicular pain and swelling and underwent radical orchiectomy. Pathology reported seminoma and received adjuvant Carboplatin for pT3 disease. He developed left testicular pain and swelling 2 months later and underwent left radical orchiectomy. Pathology reported CD4+, CD56+ high grade hematopoietic neoplasm. It was sent for second opinion to NIH and was consistent with myeloid sarcoma with monoblastic features. Repeat evaluation of right testicular specimen was CD45+. Bone marrow biopsy showed normocellular marrow with multilineage hematopoiesis. PET scan showed hyper metabolic activity in the right hemi scrotum, widespread osseous areas of increased uptake and 3 soft tissue nodules within the subcutaneous tissues of the left abdominal wall. FNA of the subcutaneous nodule showed CD56 positive monocytoid cells. Induction chemotherapy with 7+3 (cytarabine 200 mg/m2, daunorubicin 60mg/m2) with gemtuzumab 3mg/m2 on day 1, 4, 7 was completed. Cerebrospinal fluid studies (CSF) showed monoblastic/monocytic proliferation and received intrathecal (IT) chemotherapy alternating between methotrexate and cytarabine every week. CSF studies were cleared after 2 IT chemotherapy. Patient remained in the hospital for 87 days due to poor count recovery and development of pulmonary embolism. Myeloid mutation screening identified a mutation in NRASG13D. Repeat PET scan showed 7 areas of hypermetabolic foci involving nodular densities of bilateral lower anterior abdominal wall. One of the lesion was biopsied that was negative. He completed 2 cycles of high dose cytarabine for consolidation but had repeated hospital admissions and therapy was switched to azacytidine and venetoclax. Patient was evaluated by bone marrow transplant team. He had disease progression at tenth month when he presented with severe back pain and lower extremity weakness. MRI brain and spine showed new patchy T2 hyperintense signal in the right frontal white matter, increased number and size of marrow replacing lesions throughout the visualized skeleton. Patient underwent bone biopsy that showed &gt;90% marrow involvement (sheets of infiltrative cells with identical phenotype. Positive for CD56 (&gt;90% of marrow cellularity), CD4 and lysozyme. Hospital course was complicated with renal failure, electrolytes imbalance and hemodynamically instability requiring vasopressor support. Discussions were held for re-induction with CLAG (cladribine 5mg/m2, and cytarabine 2gm/m2) vs best supportive care. Patient decided to pursue comfort care and passed away peacefully.
The uniqueness of this case is the myeloid sarcoma of testes as initial presentation with normal bone marrow. Misdiagnosis is not uncommon and can delay the appropriate treatment. Extra medullary involvement from leukemia is very aggressive and needs high suspicious and prompt treatment. Systemic chemotherapy using AML-like regimens should be commenced early, even in non leukemic disease. Allogeneic hematopoietic stem cell transplantation has demonstrated promising results, particularly in patients who achieved complete remission with AML-induction protocols, and recent advances in genetic profiling may enable the development of novel targeted therapies. Prospective multicenter controlled trials are required to further refine management decisions and investigate the role of novel targeted therapies.

Disclosures
No relevant conflicts of interest to declare.