HISTORY:
                    Patient is a male in his 60s who presented with a rapidly enlarging non-tender lump in his right groin with associated firmness. The patient then proceeded with excisional lymph node biopsy.
        
                     
                
                
                
                
                 
                 
                 
                
                 
                  
                 
                
                    
                 
                            What is the most likely diagnosis?
                            
                                - Small cell melanoma
 
                                 - Merkel cell carcinoma
 
                                 - Small cell lung carcinoma
 
                                 - Diffuse large B cell lymphoma