Case 316 -- Metastasizing Tumor

Contributed by Sassan Rostami, MD and Uma NM Rao, MD
Published on line in July 2002


The patient is a 39 year-old female who was found to have a low-grade sarcoma with features of plexiform fibrohistiocytic tumor in the subcutaneous soft tissue of left posterior thigh. The tumor was resected in August 1999 and measured 3.0cm.

In August 2001 she underwent wedge resection of right lower lobe of lung for metastasizing sarcoma.

The patient was disease free until February 2002 when a CT scan of chest showed a new lesion in the left lower lobe of the lung. She also developed a 2-cm palpable mass in the medial aspect of left groin. She underwent a left groin superficial lymphadenectomy in April 2002, which showed recurrent plexiform fibrohistiocytic tumor with focal extension to one out of eight lymph nodes.


Lung metastases (August 2001): There were four firm, white, ill-defined nodules in right lower lobe of lung ranging from 0.3 to1.2cm in greatest dimensions. They were located in the periphery of lung near the pleura.

Left groin recurrence (April 2002): The tumor consisted of a 2.0-cm firm mass. On cross section, the cut surface of the mass was solid and pale gray-white. No necrosis was identified.


Lung metastases (August 2001): The neoplasm was characterized by a plump spindle cell population arranged in lobules with short fascicles and scattered multinucleated giant cells. Some areas demonstrate abundant eosinophilic collagen and others show increased cellularity with mitoses ranging from 0-2/10 high-power fields. Necrosis was not identified. Immunohistochemically, The neoplastic cells were immunoreactive for vimentin, negative for cytokeratin and focally weak positive for smooth muscle actin. The neoplastic cells were immunoreactive for C kit. CD-34 highlighted the vasculature in the tumor, but neoplastic cells were negative.

Left groin recurrence (April 2002): The bulk of tumor was located within soft tissue and focally extended to one lymph node, therefore was considered to be local extension although actual nodal metastasis could not be ruled out. No necrosis was identified. Mitotic rate was 2/10 high-power fields. The local and distant metastatic tumors were histologically similar to the primary tumor and retained the vague plexiform pattern noted in the primary site. A small subpopulation of tumor cells including the osteoclast like giant cells were CD-68 positive. CD-34, HMB 45, melan A, myogenin, pancytokeratin and S-100 stains were negative.


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