Case Presentation: A 71-year-old man with type 2 diabetes mellitus, hypertension, coronary artery disease, and peripheral arterial disease presented with worsening bilateral lower extremity pain which started two days prior to admission. Physical exam revealed cold and pale lower extremities, tenderness, and absence of pulses on both lower limbs but no edema or ulceration. Range of motion and strength were reduced secondary to pain. The remainder of the exam was normal.Laboratory results showed significant thrombocytopenia, macrocytic anemia, normal white blood cell count with 33% circulating blasts. Peripheral smear showed blasts with the presence of Auer Rods, concerning for Acute Promyelocytic Leukemia (APL), which was later confirmed by bone marrow biopsy. In addition, elevated d-dimer levels in combination with low fibrinogen and prolonged PTT were suggestive of DIC. CT angiography of lower limbs showed distal superficial femoral, popliteal, tibialis posterior, and dorsalis pedis arteries occlusion on both lower extremities. Due to his newly diagnosed APL with active thrombotic DIC, he was at high risk for worsening thrombosis or bleeding with any further surgical or interventional procedure. Therefore, a more conservative approach was taken and he was started on a heparin drip and All-Trans Retinoic Acid (ATRA). Chemotherapy was not started as it would preclude patient from undergoing emergent surgery if need be. His course was complicated by ST elevation myocardial infarction. He underwent percutaneous balloon coronary revascularization. However, he experienced multiple cardiac arrests and expired.
Discussion: AML including APL, usually presents with symptoms related to pancytopenia including easy fatigability, pallor, weakness, infections, and bleeding. APL is usually not rapidly progressive. However, it often presents as a life threatening emergency when it becomes symptomatic. Therefore, early diagnosis in subclinical stage is less expensive and more effective compared to therapeutic approaches once APL becomes symptomatic. Importantly, anemia and thrombocytopenia were present 4 months prior to this admission in our patient and timely workup could have unveiled the APL and saved his life. Although DIC is common in APL, acute limb ischemia is a rare presentation of this disease. There are few case reports of such patients worldwide and majority of them have experienced death or limb loss which shows the poor prognosis of this medical condition. As soon as patient presents with symptoms of acute limb ischemia, systemic anticoagulation (preferably unfractionated heparin) should be started to prevent further extension of thrombosis. Patients should eventually undergo one of several treatment strategies including intravascular thrombolysis, open or intravascular thrombectomy. In the presence of underlying APL, even with operative management, previous reports suggest that it carries a high morbidity and mortality. Furthermore, management of DIC as well as treatment of leukemia with ATRA and chemotherapy may influence the timing of surgery and make clinical decision making challenging.
Conclusions: APL is a type of AML which can present with DIC. In rare instances, arterial thrombosis and limb ischemia can be the presenting feature and are associated with poor prognosis. Timely diagnosis and management of APL in the sub-clinical phase, can prevent high rates of future morbidity and mortality among such patients.