These monstrous pseudotumors of the subcutis are mostly localized in the inguinal region or at (semanticscholar.org)
Hence, disseminated histiocytic sarcoma is difficult to distinguish from MH, which is a multi-system, rapidly progressive disease in which there is simultaneous involvement of multiple organs such as spleen, lymph nodes, lung, bone marrow, skin and subcutis. (caninecancer.com)
Histiocytic sarcomas occur as localized lesions in spleen, lymph nodes, lung, bone marrow, skin and subcutis, brain, and periarticular tissue of large appendicular (limb) joints. (caninecancer.com)