* <spoiler text="What is your differential diagnosis?">These groups of cells demonstrate malignant appearing cells in a background of an otherwise benign appearing lymphoid background. The atypical cells are scattered, with large nucleoli and several binucleate forms. In addition, there seem to be an increased number of eosinophils in the background. The differential diagnosis includes Hodgkin lymphoma; however, the possibility of the large atypical cells being melanoma cannot be ruled out. </spoiler>* <spoiler text="What ancillary tests would you call this on a Rapid Interpretationrecommend?">This is For this patient, we recommended that the radiologist perform a male patient with no previous history biopsy of malignancy. Our differential diagnosis can include many entities. However, these are cohesive cells the lesion so lymphoma should that it could be at sent for immunohistochemical workup. Since the bottom overall percentage of our list. We would need more information to classify these the atypical cellswere low, but we were worried that a diagnosis cell block would not contain enough of positive the malignant cells for additional stains. We also sent the lymph node for flow since a hematologic malignancy (was suspected; however, with no further specificity) can Hodgkin lymphoma, we don't expect any diagnostic findings from flow cytometry.</spoiler>* <spoiler text="What immunohistochemical stains would you do?">CD15, CD30, and PAX5 would stain tumor cells in Hodkin lymphoma. Mart1, HMB45, and S100 could be renderedused to rule out melanoma. Other additional stain in a lymphoma versus melanoma workup might include CD3, CD20, and keratin.</spoiler>

====Immunohistochemistry====<gallery heights="250px" widths="250px">CytologicallyYoursCoW20131111Biopsy7.jpg|PSA, 2x magnification. Note the predominance of brown staining in the middle.CytologicallyYoursCoW20131111Biopsy8.jpg|PSA, 60x magnification. The glands are highlighted in brown, and on the upper right the blood vessels are negative.</gallery> =====Resident Questions=====* <spoiler text="If you could only have one stain, what stain would it be?">This is a male patient with a new spinal mass. The spinal mass has glands made of cells with prominent nucleoli. In a case like this you should consider prostate as the source of the malignancy. A PSA stain would help highlight cells of prostatic origin.</spoiler><div class="usermessage mw-customtoggle-diagnosis" style="cursor:pointer">Click here to toggle the diagnosis and case discussion.</div>

* '''Positive for malignancy, the differential diagnosis includes melanoma and Hodgkin lymphoma'''. 

<gallery heights="250px" widths="250px">CytologicallyYoursCoW20131202Biopsy1.jpg|20x magnification of lymph node core biopsy.CytologicallyYoursCoW20131202Biopsy2.jpg|40x magnification of lymph node core biopsy. CytologicallyYoursCoW20131202Biopsy3.jpg|CD 15 with membranous staining.CytologicallyYoursCoW20131202Biopsy4.jpg|CD 30 with membranous staining.  </gallery> ===Biopsy Diagnosis===* '''Metastatic prostatic adenocarcinomaClassical Hodgkin lymphoma, favor mixed type'''.** CD15 Positive in tumor cells** CD30 Positive in tumor cells** PAX5 Weakly positive** CD20 Positive in background lymphocytes** CD3 Positive in background lymphocytes** S100 Negative** Mart1 Negative** HMB45 Negative ===Discussion===The features of Hodgkin lymphoma include atypical (Hodgkin cells) and Reed-Sternberg cells. The nucleus should be 3-4x the size of a small lymphocyte. In classic Hodgkin lymphoma, scattered eosinophils, plasma cells, histiocytes, and a predominately CD3+ lymphocyte population will be seen in the background. The immunophenotype of classic Hodgkin lymphoma shows CD15, CD30, MUM1, and weak PAX5 positivity. Histology is usually needed to subtype Hodgkin lymphoma.