Revisions to the International Neuroblastoma Response Criteria: A Consensus Statement From the National Cancer Institute Clinical Trials Planning Meeting.

Purpose More than two decades ago, an international working group established the International Neuroblastoma Response Criteria (INRC) to assess treatment response in children with neuroblastoma. However, this system requires modification to incorporate modern imaging techniques and new methods for quantifying bone marrow disease that were not previously widely available. The National Cancer Institute sponsored a clinical trials planning meeting in 2012 to update and refine response criteria for patients with neuroblastoma. Methods Multidisciplinary investigators from 13 countries reviewed data from published trials performed through cooperative groups, consortia, and single institutions. Data from both prospective and retrospective trials were used to refine the INRC. Monthly international conference calls were held from 2011 to 2015, and consensus was reached through review by working group leadership and the National Cancer Institute Clinical Trials Planning Meeting leadership council. Results Overall response in the revised INRC will integrate tumor response in the primary tumor, soft tissue and bone metastases, and bone marrow. Primary and metastatic soft tissue sites will be assessed using Response Evaluation Criteria in Solid Tumors (RECIST) and iodine-123 (123I) -metaiodobenzylguanidine (MIBG) scans or [18F]fluorodeoxyglucose-positron emission tomography scans if the tumor is MIBG nonavid. 123I-MIBG scans, or [18F]fluorodeoxyglucose-positron emission tomography scans for MIBG-nonavid disease, replace technetium-99m diphosphonate bone scintigraphy for osteomedullary metastasis assessment. Bone marrow will be assessed by histology or immunohistochemistry and cytology or immunocytology. Bone marrow with ≤ 5% tumor involvement will be classified as minimal disease. Urinary catecholamine levels will not be included in response assessment. Overall response will be defined as complete response, partial response, minor response, stable disease, or progressive disease. Conclusion These revised criteria will provide a uniform assessment of disease response, improve the interpretability of clinical trial results, and facilitate collaborative trial designs.

Two cases of histiocytic sarcoma with BCL2 translocations and occult or subsequent follicular lymphoma.

Histiocytic sarcoma is rare and difficult to distinguish from histologic mimics such as myeloid sarcoma due to its relatively nonspecific immunoprofile. A subset of histiocytic sarcomas are clonally related to synchronous or metachronous follicular lymphomas. Interestingly, the histiocytic tumor component has been shown to harbor BCL2 gene translocations that are identical to those found in the lymphoma. We present one case of histiocytic sarcoma and initially occult follicular lymphoma in which detection of a BCL2 gene translocation helped support the diagnosis. We also provide follow-up regarding a previously published case of histiocytic sarcoma with IGH/BCL2 fusion gene in which the patient subsequently developed follicular lymphoma and, later, diffuse large B-cell lymphoma. Our findings suggest that BCL2 gene translocations are a recurrent feature of a distinct subset of histiocytic sarcomas that are associated with follicular lymphoma; the follicular lymphoma component may be clinically occult at the time of diagnosis. Testing for an IGH/BCL2 translocation should be considered in the diagnostic workup of difficult-to-characterize neoplasms with histiocytic/monocytic morphology and immunoprofile.

Involvement of bone marrow in lymphoma: pathological investigation in a single-center from northern China.

OBJECTIVES: This study aimed to evaluate key features of bone marrow trephine biopsy (BMT) involvement of lymphoma in Northern China. METHODS: 950 cases were assessed for the occurrence of bone marrow involvement and architectural features including volume percentage, involvement pattern (diffuse, nodular, focal, para trabecular, or interstitial), and presence/absence of background changes (granuloma, stromal fibrosis or necrosis). Correlations with bone marrow aspirate (BMA) and flow cytometry (FCM) findings were made in a subset of paired cases (359 BMA and 364 FCM). RESULTS: 153 (16.1%) cases involved BMT. The most frequent type was mantle cell lymphoma (28/153, 18.3%). Architectural features were similar to previous studies except that diffuse large B-cell lymphoma (DLBCL) preferred focal pattern (16/22 cases, 72.7%) most of all. BMA and BMT agreed in 84.1% of cases (302 of 359: 277 both negative, 25 both positive), while FCM and BMT agreed in 80.8% of cases (294 of 364: 242 both negative, 52 both positive). Both varied widely among different subgroups. CONCLUSIONS: Occurrence of BMT involvement by lymphoma in Northern China is relatively low. The volume percentage, distribution patterns and background changes may be useful pointers towards a particular lymphoma type in Chinese. FCM is more sensitive and reliable than BMA in China.

WATERSHED INFARCTION IN HYPEREOSINOPHILIC SYNDROME: A DIAGNOSTIC DILEMMA IN FIP1L1-PDGFR ALPHA-ASSOCIATED MYELOID NEOPLASM.

INTRODUCTION: The FIP1L1-PDGFR alpha-positive, hypereosinophilic syndrome (HES) is a new category of hematological entities. Various clinical symptoms may occur, with no specific characteristics in either the clinical picture or the neuroimaging findings, and this may give rise to a diagnostic dilemma. A report on a long follow-up period (10 years) in a case of HES that presented with neuropsychiatric symptoms appears to be unique. Besides the complexity of the diagnostic process, the successful treatment is discussed. CASE REPORT: The HES was diagnosed in a male patient at the age of 33 years, with involvement of the central nervous system and the myocardium. After the onset of the clinical signs, the MRI indicated bilateral cerebral and cerebellar cortico-subcortical lesions involving the watershed areas, mainly in the parieto-occipital regions. High-dose intravenous steroid (methylprednisolone 500 mg/day) alleviated the neurological symptoms within a few weeks, and the administration of imatinib (200 mg/day) resulted in an impressive regression of the hypereosinophilia and splenomegaly within 6 weeks. During the follow-up, the patient has continued to receive imatinib. The molecular remission has persisted, no new complaints have developed and the condition of the patient has remained stable. CONCLUSION: The timely recognition of the HES and identification of the disease subtype which led to the administration of imatinib may be the key to successful treatment. The long stable follow-up period gives rise to a new dilemma in the treatment of the HES in these special cases: for how long should a patient receive a tyrosine kinase inhibitor, and may the treatment be suspended?

A case of rectal carcinoma with skin and bone marrow metastasis with concurrent extensive visceral involvement; unusual and dismal co-incidence.

Novel systemic therapies and modern surgical and ablative approaches have improved the survival rates for the patients with metastatic colorectal cancer. However, there are still patients with poor prognosis and underlying mechanisms that could not be defined clearly. Metastatic colorectal cancer patients with skin metastasis have a poor prognosis. A 45-year-old man, who presented with large bowel obstruction, was diagnosed with metastatic rectal adenocarcinoma. Unresectable liver metastases were found at diagnosis. FOLFOX plus bevacizumab treatment was started, but the patient developed bowel obstruction after the third cycle. Therefore, ileostomy was performed. Multiple skin, lung, liver and bone metastases appeared during that time. Bone marrow biopsy demonstrated diffuse infiltration by adenocarcinoma cells. Even though partial remission was achieved after 4 cycles of FOLFIRI-cetuximab, the disease progressed after the 8th cycle. The patient lost his life due to disease progression 8 months after the diagnosis. Bone marrow and skin are unusual sites of metastasis for colorectal carcinoma. Metastases in bone marrow and skin develop at later stages of metastatic disease. This patient lived only 4 months after the development of skin and bone marrow metastases. Skin and bone marrow metastases may be the harbingers of short survival. Biopsy of metastatic sites is crucial for diagnosis and detailed molecular analysis. Molecular pathway alterations underlying worse disease course may be found, and hence probable targets for drug improvement may be indicated.

Esophageal squamous cell carcinoma with dural and bone marrow metastases.

Patients with esophageal squamous cell carcinoma generally present at an advanced stage at the time of diagnosis. The most common sites of visceral metastasis are the lung, liver and bone, but brain and bone marrow involvement is exceedingly rare. Herein, we report a 62-year-old man with a 4-wk history of progressive low back pain with radiation to bilateral lower legs, dysphagia and body weight loss. Esophageal squamous cell carcinoma with regional lymph node, liver and bone metastases was diagnosed. He underwent concurrent chemoradiotherapy and got a partial response. Four months later, he complained of headache, diplopia and severe hearing impairment in the left ear. There was no evidence for bacterial, fungal, tuberculous infection or neoplastic infiltration. Magnetic resonance imaging of the brain demonstrated thickening and enhancement of bilateral pachymeninges and multiple enhancing masses in bilateral skull. Dural metastasis was diagnosed and he received whole brain irradiation. In addition, laboratory examination revealed severe thrombocytopenia and leucopenia, and bone marrow study confirmed the diagnosis of metastatic squamous cell carcinoma. This is the first described case of esophageal squamous cell carcinoma with dural and bone marrow metastases. We also discuss the pathogenesis of unusual metastatic diseases and differential diagnosis of pachymeningeal thickening.

[Prognostic value of the determination of bone marrow lesion in patients with neuroblastoma based on the gene PHOX2B and TH expression].

Bone marrow (BM) involvement in neuroblastoma patients is commonly detected by cytomorphology and associated with poor outcome. Molecular techniques, flow cytometry and immunocytochemistry were offered to detect low number of tumor cells in BM due to high value of analytical sensitivity, while prognostic significance of results, obtained with these methods is unclear. PHOX2B and/or TH genes expression was selected as molecular marker of BM involvement. It was determined in 411 BM samples obtained from 75 neuroblastoma patients. 263 BM samples were taken at the time of primary diagnosis, 80 during treatment and 68 before autologous stem cells (ASC) apheresis. Prognostic significance of BM involvement was defined using 5-year (in some groups 4-year) overall (OS), event free (EFS) and progression free (PFS) survival. 24 patients (32.0%) were positive for PHOX2B and/or TH expression in the BM at the time of primary diagnosis. They had decreased survival rates: EFS achieved 0.49+/-0.12, OS - 0.57+/-0.12, PFS - 0.54+/-0.12, comparing with 0.75+/-0.07, 0.80+/-0.07 and 0.77+/-0.07, respectively, in patients with negative BM, p=0.014, p=0.029 and p=0.033. The trend to decreased OS and PFS was detected in case of minimal residual disease presence at the end of the induction chemotherapy (OS and PFS both are 0.22+/-0.19 vs. 0.70+/-0.18 and 0.43+/-0.22, correspondingly, p=0.121, p=0.130). Detection of PHOX2B and/or TH genes expression in the BM before ASC harvesting led to significant decreasing of EFS and OS (0.00 vs. 0.59+/-0.14 and 0.75+/-0.13, respectively, p=0.021 and p=0.016).

A three-dimensional tissue culture model to study primary human bone marrow and its malignancies.

Tissue culture has been an invaluable tool to study many aspects of cell function, from normal development to disease. Conventional cell culture methods rely on the ability of cells either to attach to a solid substratum of a tissue culture dish or to grow in suspension in liquid medium. Multiple immortal cell lines have been created and grown using such approaches, however, these methods frequently fail when primary cells need to be grown ex vivo. Such failure has been attributed to the absence of the appropriate extracellular matrix components of the tissue microenvironment from the standard systems where tissue culture plastic is used as a surface for cell growth. Extracellular matrix is an integral component of the tissue microenvironment and its presence is crucial for the maintenance of physiological functions such as cell polarization, survival, and proliferation. Here we present a 3-dimensional tissue culture method where primary bone marrow cells are grown in extracellular matrix formulated to recapitulate the microenvironment of the human bone (rBM system). Embedded in the extracellular matrix, cells are supplied with nutrients through the medium supplemented with human plasma, thus providing a comprehensive system where cell survival and proliferation can be sustained for up to 30 days while maintaining the cellular composition of the primary tissue. Using the rBM system we have successfully grown primary bone marrow cells from normal donors and patients with amyloidosis, and various hematological malignancies. The rBM system allows for direct, in-matrix real time visualization of the cell behavior and evaluation of preclinical efficacy of novel therapeutics. Moreover, cells can be isolated from the rBM and subsequently used for in vivo transplantation, cell sorting, flow cytometry, and nucleic acid and protein analysis. Taken together, the rBM method provides a reliable system for the growth of primary bone marrow cells under physiological conditions.

Metastatic Merkel cell carcinoma in the bone marrow of a patient with plasma cell myeloma and therapy-related myelodysplastic syndrome.

Merkel cell carcinoma is an aggressive neoplasm of the skin that shows frequent lymph node metastases, but has only rarely been reported in the bone marrow. Herein we report a case of a 64-year-old male with a history of plasma cell myeloma and recent skin diagnosis of Merkel cell carcinoma who presented for a routine follow-up bone marrow to assess his myeloma. The biopsy showed persistent plasma cell myeloma, trilineage dysplasia, and clusters of neuroendocrine cells consistent with metastatic Merkel cell carcinoma. Discussion of this case, a review of metastatic Merkel cell carcinoma, and identification of clinical settings in which staging bone marrow biopsy may be warranted are presented.

Primary splenic histiocytic sarcoma complicated with prolonged idiopathic thrombocytopenia and secondary bone marrow involvement: a unique surgical case presenting with splenomegaly but non-nodular lesions.

A 67-year-old Japanese female was followed up due to prolonged idiopathic thrombocytopenia with non-response to steroid therapy for 4 years, but recent progressive pancytopenia, hypo-albuminemia, and hypo-γ-globulinemia were presented. An abdominal CT scan revealed heterogeneously enhanced splenomegaly without any nodular lesions. A splenectomy was performed, and gross examination showed markedly hyperemic red pulp, weighing 760 g, accompanied by multiple foci of peripheral anemic infarction. Surprisingly, microscopic findings exhibited a diffuse proliferation of medium-sized to large tumor cells having pleomorphic nuclei, prominent nucleoli, and abundant eosinophilic cytoplasm, predominantly within the sinuses and cords of the red pulp, which occasionally displayed conspicuous hemophagocytosis and vascular permeation. In immunohistochemistry, these atypical cells were specifically positive for CD68 (KP-1), CD163, and lysozyme, which was consistent with histiocytic sarcoma (HS) of the spleen. Subsequently, section from the aspiration of bone marrow showed infiltration of the neoplastic cells associated with erythrophagocytosis 2 months after the operation, but never before it. Therefore, primary splenic HS presenting with secondary bone marrow involvement was conclusively diagnosed. Since early diagnosis and treatment are necessary for the HS patients with poor outcomes, splenic HS should be considered as a differential diagnosis in cases with chronic thrombocytopenia and splenomegaly. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1009474924812827.

[The TH, ELAVL4 and GD2 gene expression as diagnostic markers of bone marrow lesions in patients with neuroblastoma].

The bone marrow (BM) TH, ELAVL4 and GD2 genes expression was evaluated in 331 samples from 57 different stage neuroblastoma (NB) patients, 26 BM samples from patients without NB and samples from 2 NB cell lines (IMR-32, Kelly) by real-time PCR. BM samples were considered NB-positive if PHOX2B expression was found or tumor cells were detected in BM smears. TH expression was not revealed in normal BM and was significantly lower in NB-negative samples. Expression of PHOX2B, TH and GD2 remained stable throughout NB treatment, while ELAVL4 expression was down-modulated. ROC-analysis revealed similar initial and follow-up values of TH and PHOX2B in NB patients' bone marrow making it possible to be used for disease detection and monitoring. The test prediction value was 0.994 and 0.952, respectively. The additional test for TH didn't increase the test effectiveness in comparison with PHOX2B test. ELAVL4 and GD2 assessment didn't add diagnostic value for BM involvement monitoring in NB patients.

Bone marrow metastases from anaplastic oligodendroglioma presenting with pancytopenia and hypogammaglobulinemia: a case report.

We report the case of a 40-year-old man whose bone marrow metastases occurred 57 months after the initial diagnosis and 9 months after completing radiotherapy for an anaplastic oligodendroglioma. Four months before the demonstration of visceral metastases was obtained by bone marrow biopsy, the patient developed diffuse bone pain, pancytopenia, hypercalcemia, and panhypogammaglobulinemia. These abnormalities and other clinical signs of extracranial dissemination of the primary brain tumor were initially unrecognized until the patient was admitted with the suspicion of a nonsecretory multiple myeloma. We also briefly review the factors predisposing these tumors to spread outside the CNS, albeit rarely, and discuss the clinical implications of a misdiagnosis of extracranial invasion by anaplastic oligodendroglioma, whose chemosensitivity has been definitively demonstrated.

Detection of bone marrow metastases of neuroblastoma with immunohistochemical staining of CD56, chromogranin A, and synaptophysin.

Neuroblastoma is one of the most common solid tumors occurring in childhood. Bone marrow evaluation is an important part of clinical staging in neuroblastoma patients. In view of the difficulty of detecting neuroblastoma cells with conventional bone marrow aspirate smears and biopsy (BMB) and specimens in cases in which metastasis is not prominent, we propose the use of immunohistochemistry (IHC) as a potential diagnostic tool. We examined 116 BMB and 115 bone marrow clot (BMC) specimens from 60 newly diagnosed neuroblastoma patients for tumor cells. Neuroendocrine IHC markers, such as CD56, chromogranin A, and synaptophysin were applied to diagnose neuroblastoma. Eighteen out of the 60 patients (25.4%) displayed BM metastasis, as observed with conventional hematoxylin and eosin staining. IHC staining of BMC sections was generally more sensitive than that of BMB sections for tumor cell detection. We detected tumors in 5 and 7 additional hematoxylin and eosin-negative BMB and BMC sections, respectively, using CD56. Overall, CD56 or a combination of CD56 and chromogranin A was effective in detecting neuroblastoma cells. IHC analysis of BMB and BMC sections is warranted as a routine component of the diagnostic work-up of neuroblastoma to overcome discrepancies between routine smears and IHC stains.

Thrombotic thrombocytopenic purpura as the first manifestation of metastatic adenocarcinoma in a young woman.

Thrombotic microangiopathy occurs in 5-10% of patients with mucin-producing disseminated adenocarcinoma. A 28-year-old woman complained of fatigue, bone pain, and weight loss. There were pallor, icterus, and tenderness in the bones on physical examination. Microangiopathic hemolytic anemia, leukoerythroblastic picture, thrombocytopenia, and normal coagulation tests were detected. Thrombotic thrombocytopenic purpura (TTP) was diagnosed and therapeutic plasma exchange was performed on the patient. On day 5 a laparotomy had to be performed because of acute abdomen due to the rupture of a corpus hemorrhagicum follicle of an ovary. Signet ring cell adenocarcinoma stained with cytokeratin 7 and mucicarmine was seen on ovaries and bone marrow, after the pathological examination. The primary site of tumor could not be investigated, because of the patient's refusal. Although chemotherapy including cis-platinum, infusional 5-fluorouracil, and calcium leucovorin were administered in two courses, she died from respiratory failure. In conclusion, malignancy and bone marrow involvement should be considered when associated with leukoerythroblastic picture and TTP.

Flow cytometric detection of small cell lung cancer cells with aberrant CD45 expression in micrometastatic bone marrow.

A lot of hematologists are often faced with the difficulty of diagnosing bone marrow micrometastasis of carcinoma cells. We employed a new flow cytometric immunophenotyping by a combination of CD45 with three neuroendocrine markers: CD56, microtubule-associated protein-2 and synaptophysin, and successfully detected micrometastatic tumor cells in the bone marrow of a 61-year-old male patient with small cell lung cancer (SCLC), whose marrow smears never showed a distinct morphology of metastasis. It was noteworthy that these SCLC cells accompanied the aberrant expression of CD45, leukocyte common antigen known as a specific marker for hematolymphoid neoplasms, which was not detected in the tumor of primary lesion. We describe this rare case to arouse an attention that tumors of non-hematolymphoid origin can exhibit exceptional CD45-positvity in metastatic sites.

Metastatic tumors in bone marrow: histopathology and advances in the biology of the tumor cells and bone marrow environment.

The nonhematopoietic tumors most often diagnosed in the bone marrow are metastatic. Currently, accurate diagnosis of tumor metastasis requires integration of the clinical findings; morphological features; and results of immunohistochemical stains, cytogenetics, and molecular studies. This review focuses on a practical approach to the diagnosis of metastatic tumors in the bone marrow according to current standards of practice and discusses recent advances in understanding of tumor metastasis and the interaction between tumors and the bone marrow environment.

Tumor-cell homing to lymph nodes and bone marrow and CXCR4 expression in esophageal cancer.

BACKGROUND: The chemokine and bone marrow-homing receptor CXCR4 has been implicated in metastatic dissemination of various cancers. We investigated CXCR4 expression in esophageal cancer specimens and its association with survival, lymph node microinvolvement, and bone marrow micrometastasis. METHODS: We analyzed frozen tumor specimens from 136 patients with completely resected esophageal cancer for CXCR4 expression by immunohistochemistry. Lymph node microinvolvement and bone marrow micrometastasis were assessed by immunohistochemistry with monoclonal antibodies Ber-EP4 (against epithelial cell adhesion molecule) and pancytokeratin A45-B/B3 (against several cytokeratins), respectively. Associations between CXCR4 expression and clinicopathologic features, including tumor stage, histologic grade, lymph node metastasis and microinvolvement, bone marrow micrometastasis, and survival, were investigated with Fisher's test, log-rank test, and Cox multivariable analysis. All statistical tests were two-sided. RESULTS: CXCR4 protein was expressed in 75 (55%) of 136 esophageal tumors examined. CXCR4 expression was statistically significantly associated with reduced median overall and disease-specific survival, compared with CXCR4 nonexpression (P < .001; log-rank test). The median overall survival of patients with CXCR4-positive tumors was 20 months and with CXCR4-negative tumors, 76 months (difference = 56 months, 95% confidence interval [CI] = 4 to 108 months; P < .001). The median disease-specific survival of patients with CXCR4-positive tumors was 25 months and with CXCR4-negative tumors was 97 months (difference = 72 months, 95% CI = 34 to 110 months; P < .001). CXCR4 expression was statistically significantly associated with increased lymph node microinvolvement (P < .001) and with increased bone marrow micrometastasis (P < .001). In multivariable analysis, CXCR4 expression, compared with its nonexpression, was identified as the independent variable that was most strongly associated with reduced disease-specific survival (relative risk [RR] of death = 2.03, 95% CI = 1.20 to 3.41; P = .008) and overall survival (RR of death = 2.18, 95% CI = 1.33 to 3.59; P = .002). CONCLUSION: CXCR4 expression was associated with poor clinical outcome in esophageal cancer patients. CXCR4 may have a role in early metastatic spread because its expression was associated with micrometastases to both the lymph nodes and bone marrow. Thus, CXCR4 should be explored further as a target for adjuvant therapy for micrometastatic disease.

Chemokine receptor CXCR4 expression in breast cancer as a potential predictive marker of isolated tumor cells in bone marrow.

Interactions between the CXCR4 chemokine receptor in breast cancer cells and the ligand CXCL12/SDF-1alpha are thought to play an important role in breast cancer metastases. In this pilot study, CXCR4 expression along with other biomarkers including HER2-neu and EGFR, were measured in primary tumor samples of patients with operable breast cancer to test whether any of these biomarkers alone and in combination could indicate breast cancer with high likelihood of metastasizing to bone marrow. Cytokeratin (CK) positive cells in bone marrow were identified by flow-cytometry following enrichment with CK 7/8 antibody-coupled magnetic beads. Primary tumors (n = 18) were stained with specific antibodies for CXCR4, HER2-neu, EGFR, and PCNA using an indirect avidin-biotin horseradish peroxidase method. The majority of the patients had T2/T3 tumors (72%), or lymph node involvement (67%) as pathologic characteristics that were more indicative of high-risk breast cancer. High CXCR4 cytoplasmic expression was found in 7 of 18 patients (39%), whereas 6 of 18 patients (33%) were found to have CK positivity in bone marrow. The median number of CK(+) cells was 236 (range, 20-847) per 5 x 10(4) enriched BM cells. The presence of CK(+) cells in bone marrow was found to be associated with increased expression of CXCR4 alone or in addition to EGFR and/or HER2-neu expression (P = 0.013, P = 0.005, and P = 0.025, respectively) in primary tumors. Furthermore, three patients with high CK positivity (>236 CK(+) per 5 x 10(4) enriched bone marrow cells) in bone marrow exclusively expressed high levels of CXCR4 with EGFR/HER2-neu (P = 0.001). Our data suggest that high CXCR4 expression in breast cancer may be a potential marker in predicting isolated tumor cells in bone marrow. CXCR4 coexpression with EGFR/HER2-neu might further predict a particular subset of patients with high CK positivity in bone marrow.

Bone marrow metastasis of angiosarcoma.

We report a rare finding of bone marrow metastasis from an angiosarcoma. The patient was a 36-year-old man who initially presented with a high-grade angiosarcoma of the spleen and was treated with splenectomy and chemotherapy. He developed leukoerythroblastic anemia three years after splenectomy. Bone marrow biopsy revealed extensive infiltrate by angiosarcoma with typical features of spindle tumor cells and anastomosing vascular channels. The immunohistochemistry showed tumor cells positive for the endothelial markers of CD31, CD34, and von Willebrand factor. Angiosarcomas are rare and aggressive tumors. Although metastases occur commonly, bone marrow findings have been rarely documented. We have found in the literature two other cases of bone marrow metastasis of angiosarcoma, and all these patients had a primary tumor of the spleen. It would seem that splenic angiosarcomas have a virtually unique propensity for infiltration in the bone marrow.