malignant melanoma is known for its highly unpredictable natural history and a wide array of presentations . desmoplastic malignant melanoma ( dmm ) is a rare form of malignant melanoma characterized by spindled malignant melanocytes within a fibrocollagenous stroma and may demonstrate neurotropic features . this uncommon variant accounts for < 5% of all cutaneous melanoma and was first described by conley et al . in 1971 . it commonly presents in older males on sun - exposed areas such as the head and neck [ 2 , 3 ] . five - year survival trends are comparable with similar stage non - desmoplastic malignant melanoma ( ndmm ) . later stage presentation may be more common due to a high frequency of amelanotic lesions in dmm . a 57-year - old male with a past medical history of stage iib ( t3b , n0 ) melanoma of the right superior neck and heavy marijuana use presented to the emergency department in april 2015 with progressively worsening dyspnea , right - sided pleuritic pain and hemoptysis . a subsequent chest x - ray showed right - sided hydropneumothorax with mild right - to - left mediastinal shift ( fig . a chest computed tomography ( ct ) scan confirmed the presence of a right infrahilar mass ( fig . figure  1:(a ) anterior  posterior chest x - ray showing large right - sided hydropneumothorax with mild right - to - left mediastinal shift . ( b ) chest ct showing a right infrahilar mass ( arrow ) occluding bronchus intermedius with post - obstructive airspace disease within the right lower lobe . ( a ) anterior  posterior chest x - ray showing large right - sided hydropneumothorax with mild right - to - left mediastinal shift . ( b ) chest ct showing a right infrahilar mass ( arrow ) occluding bronchus intermedius with post - obstructive airspace disease within the right lower lobe . a 14-french image - guided pigtail catheter was placed into right - sided pleural effusion draining over 2 l of purulent fluid which was sent for cytology , aerobic and anaerobic culture , and cell count . a second ct - guided chest tube was placed 3 days later due to persistent hydropneumothorax with further drainage of 200 ml of purulent fluid . subsequent catheter - directed tpa therapy initially demonstrated improvement in the effusion , but a post - procedural chest x - ray demonstrated a non - expanded lung , consistent with trapped lung . bronchoscopy revealed occlusion of the bronchus intermedius by extrinsic compression rather than from an endoluminal tumor . the bronchus intermedius was biopsied showing bronchial tissue with mild subepithelial chronic inflammation without evidence of malignancy . intra - operatively , however , a necrosis was unexpectedly found in the lower and middle lobes and resected ; on gross examination , the lower and middle pulmonary arteries and veins were thrombosed by intraluminal tumor . in addition to lobectomy , rib resection for open flap drainage was performed due to the presence of a large residual empyema space . microscopic comparison with the previous melanoma excised from the patient 's neck in 2012 was consistent with lung metastasis from that tumor . figure  2:(a ) 400 histology of infiltrating melanocytes and diffuse desmoplasia within lung parenchyma and immunohistochemistry showing tumor cells staining positive for s100 ( arrow ) . ( b ) 400 histology demonstrating periarteriolar involvement , spindle cell formation and immunohistochemistry showing tumor cells stain positive with and nuclear sox10 ( arrow ) . ( a ) 400 histology of infiltrating melanocytes and diffuse desmoplasia within lung parenchyma and immunohistochemistry showing tumor cells staining positive for s100 ( arrow ) . ( b ) 400 histology demonstrating periarteriolar involvement , spindle cell formation and immunohistochemistry showing tumor cells stain positive with and nuclear sox10 ( arrow ) . the patient experienced resolution of the empyema with drainage and removal of the associated necrotic neoplastic lung tissue . we present a case that is consistent with the usual clinical presentation of dmm : a middle - aged male with a primary tumor in the head and neck region . however , our patient 's recurrent cancer uniquely manifested as a lung mass complicated by an empyema secondary to right middle and lower lobe necrosis due to occlusive tumor vascular infiltration . dmm is known to disseminate hematogenously but very rarely presents as a lung mass , which has only been reported twice in the literature , neither of which were associated with an empyema [ 4 , 5 ] . in contrast to ndmm , which may spread to distant sites , dmm exhibits a more sarcomatoid local recurrence pattern . regional lymph node involvement is detected up to 13.7% of the time in pure and mixed dmm . strong and diffuse s100 and sox10 immunohistochemical staining was observed in this case , which is necessary to confirm the diagnosis , since conventional melanocyte - specific markers ( melan a and hmb45 ) are characteristically negative in dmm ( 4 , fig .  2 ) . the role of both radiation and immunotherapy or chemotherapy is under investigation , as dmm 's hybrid morphology and recurrence pattern suggest that it may respond to treatment similarly to sarcoma or ndmm [ 2 , 7 ] . there are currently no standardized treatment strategies other than complete surgical resection with adequate margins , which achieves 5-year survival in 61% of patients . the long - term clinical course of dmm is variable and typically results in local recurrence , though distant metastases occur in 15% of patients . previous studies in ndmm suggest that greater depth of invasion correlates with the development of systemic metastases . we observed a disease - free interval of nearly 3 years prior to detection of the lung mass . this case illustrates a unique presentation of recurrent dmm with lung mass and empyema years after primary tumor resection , reminding clinicians to maintain a high index of suspicion for atypical modes of recurrent tumor presentation in dmm patients .
desmoplastic malignant melanoma ( dmm ) is an extremely rare subtype of cutaneous melanoma that has diverse clinical presentations . 
 we describe the unique case of a 57-year - old man presenting with empyema secondary to vascular occlusion from metastatic dmm . 
 only two other cases of dmm presenting as a lung mass have been previously reported in the literature . 
 this report highlights potential insidious pathology of dmm , which requires a high clinical suspicion to properly diagnose and manage .