| Abstract|| |
Rhabdomyosarcoma (RMS) masquerading as acute leukemia (AL) is very rare. We report a case which presented as acute leukemia subsequently diagnosed to be Alveolar RMS of Urinary Bladder. Although cases of RMS with leukemic presentation have been reported, to our knowledge this is the first case of Alveolar RMS of Urinary Bladder with leukemic picture at initial presentation. We would like to emphasize that this critical error can have serious consequences on the treatment and outcome of these patients.
Keywords: Acute leukemia, bone marrow, flow cytometry, immunohistochemistry, rhabdomyosarcoma
|How to cite this article:|
Jagdale RV, Pol JN. Alveolar rhabdomyosarcoma of urinary bladder presenting as acute leukemia: A diagnostic trap. Indian J Pathol Microbiol 2020;63:623-6
|How to cite this URL:|
Jagdale RV, Pol JN. Alveolar rhabdomyosarcoma of urinary bladder presenting as acute leukemia: A diagnostic trap. Indian J Pathol Microbiol [serial online] 2020 [cited 2020 Nov 24];63:623-6. Available from: https://www.ijpmonline.org/text.asp?2020/63/4/623/299331
| Introduction|| |
Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood and adolescence. Approximately 6-23% of RMS are associated with bone marrow (BM) metastasis. Massive BM involvement of RMS is not unusual but mimicking of leukemia is rare. Differentiation between acute leukemia (AL) and BM metastasis of RMS is challenging because diffuse involvement with blast like cells is common in both. The similarities in clinical presentation compounded by morphological alikeness can result in incorrect or delayed diagnosis.
We describe a case presenting as AL eventually diagnosed to be Alveolar RMS of Urinary bladder (UB).
| Case Report|| |
A 19-year-old male presented with bodyache, generalized weakness, and hematuria for 2 weeks. His peripheral smear revealed anemia, thrombocytopenia with leukoerythroblastic blood picture and the presence of 8% blasts.
BM aspiration showed 92% blast-like cells [Figure 1] which were negative for Myeloperoxidase, Periodic acid-Schiff and Sudan Black B. His BM biopsy showed scattered and clusters of small round cells in the intertrabecular spaces with fibrosis and virtual absence of trilineage hematopoietic elements [Figure 2]a. Imaging studies revealed a 7 × 6 cms soft tissue mass in UB with mild splenomegaly and bilateral pleural effusion. Cystoscopic biopsy of UB mass was performed and reported as non-Hodgkin lymphoma/acute lymphoblastic leukemia (ALL) [Figure 2]b, [Figure 2]c, [Figure 2]d.
|Figure 1: Bone marrow aspiration smears showing blast-like cells. Leishman stain (a) ×40 (b) ×100|
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|Figure 2: (a) Bone marrow biopsy showing infiltration by blast-like cells with fibrosis. Inset shows ×40 magnification.(b, c & d) Urinary bladder biopsy showing subepithelial infiltration by tumor cells (b) in alveolar pattern (c) and having blast-like round cell morphology. (a and d) ×40), (b and c) ×10|
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He was referred to our center with a diagnosis of AL for further management. A new BM aspirate was performed at our center for immunophenotyping. Morphologically, the BM aspirate revealed diffusely arranged clusters of atypical cells with large round nuclei with moderate bluish vacuolated cytoplasm.
Although the morphologic findings were suggestive of ALL, the results of flow cytometry (FC) were not supportive of this diagnosis. A negative CD45, MPO, TdT, myeloid, and lymphoid markers [Figure 3] pointed to the diagnosis of a non-hematological neoplastic infiltration. Immunohistochemistry (IHC) done on BM biopsy [Figure 4]a and [Figure 4]b and UB biopsy [Figure 4]c and [Figure 4]d revealed tumor cells expressing desmin and myogenin and negative for CD45, CD99, TdT, MPO, CD10, CD138, S-100, Synaptophysin, Cytokeratin, and EMA. Cytogenetic studies revealed a karyotype of t (2;13) (q35;q12),+12 [Figure 5]. Thus, a diagnosis of Alveolar RMS of UB infiltrating the BM was made.
|Figure 3: Flow cytometry analysis showing blastoid cells negative for CD45 & all myeloid (CD13, CD33, CD117, MPO), lymphoid (CD3, CD5, CD7, TdT, CD10, CD19), erythroid (Glycophorin a) and megakaryoblastic (CD41a) markers|
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|Figure 4: (a and b) IHC of bone marrow biopsy tumor cells express (a) Desmin (×10) and (b) Myogenin (×40). (c and d) IHC of Urinary bladder biopsy tumor cells express (c) Desmin (×40) and (d) Myogenin (×40)|
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|Figure 5: Marrow karyotyping showing a karyotype of t(2;13)(q35;q12),+12|
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He was started on combination chemotherapy of vincristine, dactinomycin, cyclophosphomide, ifosfamide, and etoposide and also received local radiotherapy. However, due to financial constraints, he discontinued the treatment and died a year later.
| Discussion|| |
Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood and adolescence. Most of these tumors originate in the head and neck region, urogenital tract, and extremities. Fewer than 25% of the patients have distant metastasis which mainly occurs in lung, BM (23%), lymph nodes, bones, omentum and pleura. Almost all the reported cases associated with marrow involvement including those presenting as possible AL have been of the alveolar type with a dismal progress.
RMS with marrow involvement may present with fever, weakness, weight loss, anemia, bleeding manifestation, lymphadenopathy, hepatosplenomegaly, and disseminated intravascular coagulation. It can be confused with AL, especially ALL and some cases can mimic AL at presentation and thus mislead the diagnosis. On PubMed English literature search, 42 cases of RMS with leukemic picture are reported of which 39 cases had AL at presentation. In the Indian context, total 6 cases of RMS with leukemic presentation have been described.,,,,, Most of these cases had primary either in the head and neck, urogenital tract or soft tissue; in some cases primary site was not identified.,, To our knowledge, this is the first case of Alveolar RMS of UB with bone marrow infiltration and AL like picture at presentation.
Sandberg at al. reviewed 26 cases of RMS presenting as AL from 1972 to 2000. The median age at presentation was 18.5 years with a striking male predominance. The median survival was 8 months. Lopez-Andrade et al. added 16 more cases taking the tally up to 42 cases. Commonly reported immunophenotype was CD56+/CD45- and was useful for the correct diagnosis in 45% of the cases.
Non-hematolymphoid tumors presenting in leukemic phase, diffuse marrow infiltration or in apparent primary can be mistaken for hematolymphoid malignancies. The tumors commonly mistaken for AL are RMS, neuroblastoma, medulloblastoma, anaplastic oligodendroglioma, small cell carcinoma, Ewing sarcoma, and neuroendocrine tumor. Patients with widespread RMS can present with systemic symptoms, pancytopenia, leucoerythroblastic picture, disseminated intravascular coagulopathy, and thus clinically mimic AL. BM metastasis of RMS reveals a loosely arranged distribution of cells resembling blasts thus simulating AL. There are case reports of RMS misdiagnosed and treated as poorly differentiated leukemia based on morphology and cytochemistry alone and then proved as RMS based on IHC or demonstration of t (2;13)(q35;q14) by cytogenetic study. IHC and FC play an important role to avoid misdiagnosis as these cells are negative for CD45 and myeloid and lymphoid markers. Certain morphological clues are syncytial clumps of tumor cells, cytoplasmic vacuoles and multinucleation. Along with the expression of immunohistochemical markers like desmin and myogenin, the presence of translocation t(2;13)(q35;q14) is pathognomonic. In today's scenario where these specialized diagnostic tests are considered practically mandatory, the probability of misdiagnosis is less. Nevertheless, it is important to recognize this presentation, as loss of valuable time and resources may adversely affect the treatment and outcome of these patients.
We conclude that RMS should be included in the differential diagnosis of children and adolescents with undifferentiated CD45 negative blast-like cells in BM. A multi-disciplinary approach using a combination of IHC, FC, and cytogenetic studies is crucial in establishing the diagnosis.
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Conflicts of interest
There are no conflicts of interest.
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Rakhi V Jagdale
Department of Pathology, Shri Siddhivinayak Ganapati Cancer Hospital, Miraj, Sangli - 416 410, Maharashtra
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]