In June 2004, a 21-year-old white woman presented with spiking fevers, bruising, shortness of breath, and malaise. Laboratory findings revealed a white blood cell count of 21,700/muL with 47% circulating blasts. Subsequent bone marrow evaluation demonstrated AML with del(9q). Lumbar puncture was negative for cerebral spinal fluid (CSF) involvement. The patient underwent prompt treatment with cytarabine (Ara-C) 200 mg/m2 continuous infusion for seven days and idarubicin 12 mg/m2 daily for three days. Bone marrow evaluation at day 14 revealed residual leukemia, and repeat bone marrow evaluation three weeks later was negative. The patient subsequently received consolidative treatment with four cycles of high dose Ara-C. 
While receiving the chemotherapy, the patient developed pain in her left shoulder which radiated down the left arm from the elbow into the ulnar two fingers with numbness in those digits. The pain progressed, and further work-up was pursued including electromyography (EMG), which was consistent with an ulnar neuropathy. The patient underwent transposition of the ulnar nerve and carpal tunnel release because of new slight thumb numbness. The patient's symptoms progressed despite the procedure to include impaired dorsiflexion of the left great toe, numbness of her right calf, and numbness and weakness of the right thumb and index finger. Ten months after her initial diagnosis, associated fatigue prompted a repeat bone marrow evaluation, which was consistent with relapsed AML. Magnetic resonance imaging (MRI) of the brachial plexus and lumbar spine revealed bilateral brachial plexus involvement by a presumed chloroma and leukemic infiltration of the left and right lumbosacral plexus.
The patient initiated treatment with mitoxantrone and etoposide. Repeat bone marrow evaluation was negative and repeat MRIs of the brachial plexus and lumbar spine demonstrated resolution of the leukemic involvement. While post-treatment biopsy of the chloroma sites was not performed, it was felt that based on the available imaging, clinical improvement, and bone marrow aspiration results, that the patient had attained a complete response to treatment. The patient underwent an unrelated donor-matched allogeneic bone marrow transplant. The conditioning regimen included total body irradiation (TBI) to 1375 cGy in 11 fractions administered three times daily with a consolidative boost to the left brachial plexus to 600 cGy in four daily fractions. The boost was added because residual microscopic disease could not be ruled out. Graft versus host disease (GVHD) prophylaxis included tacrolimus plus methotrexate. 
Repeat bone marrow aspiration posttransplant demonstrated cytogenetic remission with full donor chimerism and normal karyotype. The patient completed five monthly doses of intrathecal Ara-C (70 mg) as central nervous system (CNS) prophylaxis. Cytopathology on all the CSF samples was negative for malignancy. The patient's posttransplant course was complicated by hepatic fungal infections, GVHD, involving the upper gastrointestinal tract and liver, and renal insufficiency resulting in a very slow but physically remarkable recovery to eventually include triathlon training. While on immune suppression including tacrolimus and prednisone, the patient developed leukemia cutis of the right chest that resolved completely with the tapering of immunosuppressive medications. A bone marrow evaluation at the time of the skin biopsy revealed a normal karyotype, all donor by diagnostic molecular pathology.
Approximately one year posttransplant, the patient developed progressive left intrinsic hand weakness with an associated palpable mass in her left upper extremity. An MRI study was consistent with a chloroma of the biceps brachi along the course of the musculocutaneous nerve. Fine needle aspiration of the mass was consistent with leukemic infiltration; CSF analysis and bone marrow aspiration at the time of the peripheral nerve biopsy were negative for leukemic involvement, and polymorphism analysis with DNA primers demonstrated complete donor engraftment. The patient received a course of radiation therapy to 3000 cGy in 15 fractions to the mass, with complete clinical resolution of the lesion by treatment completion. 
Seven months after completion of the patient's last course of radiation, she developed new right arm and leg pain. Work-up including MRIs demonstrated three presumed chloromas near the right elbow (ulnar nerve), right upper deltoid (axillary nerve), and right psoas region (lumbar plexus). Biopsy of the right psoas lesion was consistent with chloroma (Figure 1); CSF analysis and bone marrow biopsy were negative and polymorphism analysis did not detect any host cells. The patient underwent her third course of radiation to the right elbow, right deltoid region, and right paraspinal psoas mass, each to 2400 cGy in 12 fractions. All sites demonstrated a clinical and radiographic response (Figure 1) on followup. Three months after completion of treatment, the patient developed new pain in her left first and second toes. Imaging was consistent with a left peroneal nerve chloroma for which she received 2400 cGy in 12 fractions.
The patient had been completely tapered off immunosuppression and was doing well on no further therapy until 14 months later, when she palpated a new mass in her left forearm, which was biopsied and consistent with a leukemic infiltrate. Further work-up did not reveal any systemic disease with bone marrow evaluation showing full donor chimerism and no CSF involvement. The patient was neurologically asymptomatic; however, neurological examination was consistent with median nerve involvement. A course of 2400 cGy in 12 fractions to the left forearm was initiated with clinical resolution. Despite the patients multiple recurrences and courses of radiation, she remained in excellent physical condition with continued participation in triathlons and road races. 
Despite receiving a low dose donor lymphocyte infusion of 1 x 105 CD3+ cells/kg several months before, the patient developed right lower extremity weakness along the femoral distribution approximately one year after her last radiation treatment. MRI, computerized tomography (CT), and positron emission tomography (PET) were consistent with a right femoral nerve chloroma extending into the right inguinal canal (Figure 2). The patient received another course of 2400 cGy in 12 fractions with a cone down to avoid overlap with the prior radiation field (right psoas chloroma). Clinical improvement was observed during the course of treatment without any associated treatment toxicities. Repeat MRI one month after treatment demonstrated complete resolution.
Since completion of her last course of radiation therapy, she has received no further therapy and has not shown any evidence of recurrence of chloroma or leukemia; the patient plans to resume her triathlon training.