Cutaneous and subcutaneous pleomorphic liposarcoma: a clinicopathologic study of 29 cases with evaluation of MDM2 gene amplification in 26.

[dedifferentiated liposarcoma]

Pleomorphic liposarcoma (PL ) is an uncommon form of liposarcoma that rarely occurs in the skin and subcutis . As its behavior in this setting is incompletely characterized , we undertook a study of a series of superficial PLs , defined as those arising or based primarily in the dermis and /or subcutis without involvement of deep structures . In addition , MDM 2 gene amplification , a diagnostic signature of well-differentiated /dedifferentiated liposarcoma (WDL /DL ), was evaluated to address the recent observation that this gene is amplified within PL-like areas in DL . PLs were obtained from institutional and consultation files (n =29 ). Cases were evaluated with respect to age , sex , location (dermis , dermis and subcutis , subcutis ), size , predominant pattern (pleomorphic spindled or epithelioid ), extent of lipogenic differentiation , and tumor necrosis . MDM 2 amplification was analyzed using FISH on formalin-fixed , paraffin-embedded material in 26 cases . Patients ranged in age from 5 to 93 years (M :F =1 .4 :1 ). Tumors were located on the extremity (n =15 ), trunk (n =7 ), and head and neck (n =7 ) and involved the dermis (n =4 ), dermis and subcutis (n =10 ), and subcutis (n =15 ). Tumor size ranged from 0 .8 to 15 cm (median =2 cm ). All were mitotically active high -grade sarcomas [FNCLCC grade 2 (n =23 ) or 3 (n =6 )] with either a pleomorphic spindled (n =24 ) or an epithelioid pattern (n =5 ) with variable extent of lipogenic differentiation [<25 % (n =15 ), 25 % to 50 % (n =9 ), >50 % (n =5 )]. Necrosis was present in 3 cases . MDM 2 gene amplification was present in 3 of 26 cases . Follow-up information in 24 cases (range =1 to 192 mo ; median =48 mo ; mean =59 mo ) revealed local recurrences (4 /24 ) but no metastasis or death from disease . We conclude that cutaneous and subcutaneous PLs , despite their high grade , have a much more favorable outcome compared with their deep -seated counterparts , most likely attributed to their small size and superficial location . The low incidence of MDM 2 gene amplification in our series indicates that most superficial PLs are unrelated to WDL /DL . PL likely evolves by way of more than 1 molecular pathway .

Diseases
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Diseases presenting "have a much more favorable outcome compared with their deep-seated counterparts" symptom

dedifferentiated liposarcoma

pleomorphic liposarcoma

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