Histology Laboratory, Indiana Medical History Museum
IAP Case of the Month for August 2015
A 33-year-old male with lump in left thigh back.
Rasha Salama, M.D.
IU Department of Pathology and Laboratory Medicine Residency Program, PGY-3
Clinical history: A 33-year-old male started feeling some discomfort in the posterior aspect of his left thigh back while sitting in 2013. He later developed a lump at the back of his thigh so he finally sought medical care in 2014. His primary care physician at first thought it was bursitis and recommended nonsteroidal anti-inflammatory drugs and physical therapies. However, the mass continued to increase in size and the pain became more significant. An MRI was ordered and showed 12.5 x 14.5 x 18.6 cm enhancing soft tissue mass with multiple septations and central necrosis. The bone did not appear to be involved. The patient also had a chest CT scan that showed several noncalcified subcentimeter lung nodules suspicious for metastatic disease. FNA was performed and diagnosis was rendered. The patient underwent chemotherapy prior to the surgical intervention; however, the treatment did not seem to work and it metastasized to the left inguinal lymph node, right shoulder, left back, and multiple abdominal subcutaneous locations.
Gross Examination: (Figure 1).
Microscopic examination: Histologic sections from the thigh tumor resection
(If you are using Windows PC, right click on the image, open in a new tab and then zoom)
(Hematoxylin-eosin, original magnification _X40)
(Hematoxylin-eosin, original magnification _X200)
(Hematoxylin-eosin, original magnification _X400)
(Pan cytokeratin immunostaining, AE1/AE3 (immunoperoxidase, original magnification _X100)
INI-1 immunostaining (immunoperoxidase, original magnification _X40)
(Myogenin immunostaining (immunoperoxidase, original magnification _X40)
S100 immunostaining (immunoperoxidase, original magnification _X40)
Vimentin immunostaining (immunoperoxidase, original magnification _X100)
B- Epithelioid malignant peripheral nerve sheath tumor
C- Epithelioid angiosarcoma
D Epithelioid rhabdomyosarcoma
E- Epithelioid monophasic synovial sarcoma
F- Extrarenal rhabdoid tumor
G- Undifferentiated carcinoma.H- Epithelioid sarcoma, proximal type.