Monoblastic sarcoma cutis preceding acute monoblastic leukemia
Authors: Efstathios Rallis, Evgenia Stavropoulou, Ilias Michalakeas, Pavlos Papadakis, Christos Poziopoulos
Journal: American Journal of Hematology (2008)

Myeloid sarcoma is an extramedullary tumor that typically occurs in the setting of acute myeloid leukemia or myeloproliferative disorders.Monoblastic sarcoma (MS) is a rare (3%) type of myeloid sarcoma, with poor prognosis [1].We present a case of an extensive MS involving solely the skin (leukemia cutis) with no other abnormal physical or laboratory finding at presentation, in an adult male.A 78-year-old male was referred to our clinic because of the appearance of papules and nodules of 1-month duration, involving the trunk and the extremities.The lesions were pink to skin-colored firm papules and variably-sized nodules with a bruise resembling appearance.The patient was in good general condition, and no palpable lymphadenopathy, organomegaly, or gingival hypertrophy was observed.The peripheral blood count was normal.There was a history of colorectal cancer, diagnosed 6 years ago and treated by surgical excision only.A punch biopsy was initially performed, and the histological examination revealed full-thickness infiltration of the dermis by large atypical mononuclear cells with a perivascular distribution.The tumor cells were positive for CD34, CD56, and CD68 (KP1) and were negative for MPO, CD4, and CD5, leading to the diagnosis of MS cutis (WHO ICD-O code 9930/3).Approximately 1 month after the first examination, the patient was admitted for further evaluation and treatment.The laboratory findings revealed mild anemia, with 7% monoblasts in the peripheral blood examination.Bone marrow investigation showed a 35% infiltration by monoblasts.These findings led to the diagnosis of acute monoblastic leukemia (WHO ICD-O code 9891/3).Cytogenetic study (band staining) was not successful because of the low mitotic rate of the marrow cells.A combined chemotherapeutic regimen (IDA 12 mg/m 2 , ARA-C 100 mg/m 2 CI, Days 1-5, VP-16 100 mg/m 2 , Days 1-3,) was initiated and it was well tolerated.The skin lesions initially improved, but unfortunately the disease became chemoresistant 3 months later.CNS involvement was established and the skin lesions expanded, coalescing into numerous indurated plaques and nodules (Images 1-3).The lesions, in combination with edema, produced a leonine face (see Image 1).The patient developed progressive pancytopenia and finally passed away 8 months after admission.MS may occur de novo or as a manifestation of relapse in patients previously treated for primary or secondary acute myeloid leukemia.These tumors represent the tissue phase of the hematological disease and can involve any part of the body, but commonly involved sites include subperiosteal bone structures of the skull, paranasal sinuses, the sternum, ribs, vertebrae, and pelvis.Lymph nodes and skin are also common sites of involvement [2].It is almost impossible to distinguish MS from granulocytic sarcoma and other types of small-round cell tumors on the basis of morphologic examination alone.Immunohistochemistry is mandatory for a correct diagnosis.Cutaneous lesions of leukemia can be classified into two groups, leukemoids or nonspecific lesions and true leukemic infiltrations or specific lesions (leukemia cutis) [3].The cases of aleukemic leukemia cutis reported in the literature are limited and show little or no conformity in their clinical appearance [4][5][6][7][8].Image 1. Papules and nodules producing a leonine face.