© Angel Fernandez Flores, MD, PhD Synovial sarcoma

 

Synovial sarcoma

 

Clinical presentation

A small nodule that increases rapidly in size.

Usually accompanied by a deep mass.

 

Morphology

Tumor arranged in fascicles of spindle cells. This is the only component in the monomorphic type.

Herringbone pattern is only focal.

Necrosis only focal if evidenced.

The cells are bland and monomorphous.

Hemangiopericytomatous vessels are common.

In the biphasic type, there is a glandular component lined by synovial-like cells.

 

 

 

Immunohistochemistry

TLE1 commonly positive.

Cytokeratin+ in the biphasic type.

 

Genetics

t(X;18)(p11;q11) is found. This translocation fuses the SYT gene from chromosome 18 to either of 2 homologous genes at Xp11, either SSX1, SSX2, or SSX4.

The biphasic type usually expresses the SYT-SSX1 transcript.

The monophasic type may express either transcript.

 

Main differentials

Glandular malignant peripheral nerve sheath tumor: cells can be large and pleomorphic.It many times involve nerves. No hemangiopericytomatous vessels. No SYT-SSX gene fusion. TLE1 ususally negative.

Diffuse type tenosynovial giant cell tumor: No SYT-SSX gene fusion. Giant cells may be frequent. Sometimes grooved nuclei are found.

Carcinosarcoma: No SYT-SSX gene fusion.Sometimes pleomorphic.

Epithelioid sarcoma: commonly superficial. Extensive necrosis.No hemangiopericytomatous vessels. No SYT-SSX gene fusion. TLE1 ususally negative. CD34 commonly+. CA125 commonly+.

Fibrosarcoma: Diffuse herringbone pattern. No hemangiopericytomatous vessels. No SYT-SSX gene fusion. TLE1-.

Leiomyosarcoma: usually pleomorphic cells. Actin+. No hemangiopericytomatous vessels. No SYT-SSX gene fusion. TLE1 ususally negative.

Clear cell sarcoma: prominent nuclei. Melan-A+, HMB45+. t(11;12) is common.

Palmar or plantar fibromatosis: multiple small nodules. No SYT-SSX gene fusion. variable cellularity.

 

© Angel Fernandez Flores, MD, PhD