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The patient is an 60 64 year old white male who presented with a remote history of an abdominal melanoma that was excised with negative margins. The patient has been experiencing lower left sided back pain for the past several months and has received epidural injections. As Imaging showed a part of the workup, the patient had left perinephric retroperitoneal hematoma and a CT which revealed retroperitoneal lymphadenopathyleft renal lower pole cystic lesion with hemorrhage. Additional imaging showed numerous pulmonary lesions. A CT An endobronchial ultrasound guided fine needle aspiration and biopsy of a paracaval lymph node was performedscheduled.

* 2003 MelanomaCongestive heart failure* DiabetesVentricular tachycardia* HypertensionIschemic heart disease

* 2013 Arthroscopic knee surgeryCoronary stent placement* 2003 Excision Implant of melanoma* 2002 DiscectomyAICD

The differential diagnosis for otherwise asymptomatic lymphadenopathy in this patient concern is melanoma, lymphoma, or occult a primary renal malignancywith metastatic disease to lungs. An endobronchial ultrasound guided FNA is scheduled. An onsite rapid diagnosis by cytology was scheduled.

* PET CT showed hypermetabolic activity with an SUV of 12.7Abdomen shows a large perinephric hematoma and large low anterior structure in left lower pole suspicious for a hemorrhagic renal cell carcinoma. * CT of abdomen and pelvis showed adenopathy adjacent to the aorta and inferior Chest shows multiple small lung lesions measuring up to the vena cava at the level of the right kidney. The largest node measured 4 cm 13x12 mm in greatest dimension.==Pathology==

===CytologyImmunohistochemistry===

CytologicallyYoursCoW20131209Cytology1CytologicallyYoursCoW20131209Cytology5.jpg|4x magnification of a PAX8 on 4R lymph node. There is a polymorphic lymphoid population with scattered large atypical cells.CytologicallyYoursCoW20131209Cytology2.jpg|20x magnification of paracaval lymph node. There are small lymphocytes with background lymphoglandular bodies. Scattered eosinophils and large atypical cells with prominent nucleoli.CytologicallyYoursCoW20131209Cytology3.jpg|40x magnification of paracaval lymph node. There are atypical binucleated cells among the large atypical cellsshows positive nuclear staining.

* <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 other immunohistochemical stains that would be an increased number of eosinophils applicable in the background. The differential diagnosis includes Hodgkin lymphoma; however, the possibility of the large atypical cells being melanoma cannot be ruled out. </spoilerthis case?">* <spoiler text="What ancillary tests would you recommend?">For this patient, we recommended that the radiologist perform a biopsy of the lesion so that it could be sent for immunohistochemical workup. Since the overall percentage of the atypical cells were low, we were worried that a cell block would not contain enough of the malignant cells for additional stains. We also sent the lymph node for flow since a hematologic malignancy was suspected; however, with Hodgkin lymphoma, we don't expect any diagnostic findings from flow cytometry.</spoiler>RCC*CD10*PAX2* <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 used to rule out melanoma. Other additional stain in a lymphoma versus melanoma workup might include CD3, CD20, and keratin.Kidney specific antigen</spoiler> 

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* '''Positive for malignancy, the differential Rapid diagnosis includes melanoma and Hodgkin lymphoma''': Non-small cell carcinoma.* Final diagnosis: Renal cell carcinoma.