ISPUB.COM The Internet Journal of Oncology Volume 8 Number 2 1 of 5 Rhabdomyosarcoma with Bone Marrow Infiltration: A Diagnostic Dilemma R Khanna, D M, S Belurkar, C Manohar, S Ray, P Srilatha, N Suvarna Citation R Khanna, D M, S Belurkar, C Manohar, S Ray, P Srilatha, N Suvarna. Rhabdomyosarcoma with Bone Marrow Infiltration: A Diagnostic Dilemma. The Internet Journal of Oncology. 2012 Volume 8 Number 2. Abstract Rhabdomyosarcoma is the most common soft tissue sarcoma in children and adolescents. In adults, the prevalence is much lower. Most patients present with a mass in the head and neck region, urogenital region or even with distal extremity involvement. A bone marrow infiltration at the time of clinical presentation has also been documented in literature. But a simultaneous marrow infiltration can simulate a hematopoietic neoplasm, leading to diagnostic errors. We document one such challenging case of a 47 year old male patient presenting with bicytopenia. Patient was hospitalized following a referral due to a mass in the left cheek, diagnosed earlier as clear cell sarcoma. Bone marrow aspirates yielded a dry tap, with sinusoidal blood and both the aspirate as well as the imprint smear showed pleomorphic cells with vacuolated cytoplasm. The corresponding trephine biopsy showed diffuse and interstitial infiltrates of rhabdoid cells with focal areas of infarct. Considering the morphological details, a diagnosis of rhabdomyosarcoma was rendered after ruling out other possibilities. A review of the lesional biopsy with ancillary techniques eventually corroborated the bone marrow diagnosis. INTRODUCTION Rhabdomyosarcoma (RMS) stands as the most common soft tissue sarcoma in children younger than 15 years 1 . In adults, the incidence is much lower after the age of 45 with various studies showing an average prevalence of 2-5% 1 . It is presumed to arise from a primitive mesenteric cell rest committed to the skeletal muscle differentiation 2 . According to the World Health Organization 3 classification, there are three subtypes in order of prevalence: embryonal, alveolar and pleomorphic. While the embryonal RMS is most often seen in the head and neck region, the other two are reported in the distal extremities. Regardless of the subtype, the tumor is notorious to disseminate widely at the time of clinical presentation. The most common sites of metastases include lungs, lymph nodes and bone marrow 1 . The bone marrow involvement is seen in about 30% of cases of metastasis 4 . Etcubanas et al 5 reported a series of 10 cases of metastatic rhabdomyosarcoma, in which an extensive search for the primary was futile. They explained the cytological details and the difficulties in making a diagnosis in such cases, without assessing the involvement of bone marrow. More recently, Reid and colleagues 6 in their paper shed light on the histological features of RMS infiltrating the bone marrow. Since then, frequent case reports have followed. Although ancillary techniques have certainly enhanced the diagnostic precision, the morphological overlap with other hematopoietic neoplasms has puzzled many pathologists. We report a case of alveolar rhabdomyosarcoma infiltrating the bone marrow at the time of clinical presentation. CASE REPORT A 47 year old male patient, laborer by occupation was referred to our hospital with a diagnosis of clear cell sarcoma of the oral cavity, which was diagnosed elsewhere. He complained of generalized body ache, loss of appetite and significant weight loss. He also provided history of pain during chewing and a disturbing cough. Per oral examination revealed a 2x1 cm swelling in the left buccal mucosa with overlying ulceration. Further examination showed multiple level 1 lymph nodes in the left side. Following hospitalization, the hematological investigations comprising of complete hemogram and a peripheral smear examination revealed a bicytopenic profile with anemia and thrombocytopenia. Occasional nucleated red blood cells were also seen in the smear. A bone marrow study was requested to elucidate the reason for bicytopenia and a possible infiltration. Meanwhile, radiological investigations (CT scan) revealed few ill defined nodules in both lungs with minimal pleural