Initial pathology was low-grade sarcoma or myxosarcoma
. Immunohistochemical (IHC) stains on paraffin sections were reactive to vimentin, focally reactive to desmin, but negative for S100, indicating the mass was mesenchymal and connective tissue in origin, most consistent with a sarcoma.
 F 29 Angiosarcoma F 42 Sarcoma F 49 Myxosarcoma
Michler et al.
A third category, "spindle-cell or myxosarcoma
," comprised rare tumors that were thought to derive from the stroma.
In that study, there were no cases of myxoma or myxosarcoma
, and only two neoplasms were diagnosed in pintagols: cloacal papilloma and subcutaneous liposarcoma.
Xiao, "Cardiac myxoma and myxosarcoma
: clinical experience and immunohistochemistry," Asian Cardiovascular and Thoracic Annals, vol.
Left atrial myxosarcoma
with systemic metastasis: a case report.
The distinction between a poorly differentiated leiomyosarcoma and other spindle cell tumors such as rhabdomyosarcoma, fibrosarcoma, schwannoma, and myxosarcoma
Soft-tissue sarcomas are tumors arising from extraskeletal connective tissues and from Schwann cells and include fibrosarcoma, liposarcoma, hemangiopericytoma, rhabdomyosarcoma, lymphangiosarcoma, malignant fibrous histiocytoma, leiomyosarcoma, myxosarcoma
, myxofibrosarcoma, mesenchymoma, spindle cell tumors, and malignant peripheral nerve sheath tumors (neurofibrosarcoma, Schwannoma).