Surgical Pathology Criteria

Mammary Type Myofibroblastoma

Definition

Note: the following are related in name only

Diagnostic Features

Differential Diagnosis

Mammary Type Myofibroblastoma

Spindle Cell Lipoma

Cellular Angiofibroma

Usually diffuse collagen

Ropey collagen

Wispy collagen with prominent round vessels

Desmin positive

Desmin negative

Desmin variable

All are CD34 positive with loss of Rb due to 13q14 abnormalities;  all are benign

 

Mammary Type Myofibroblastoma

Solitary Fibrous Tumor

Desmin positive

Desmin negative

Loss of Rb

Rb positive

STAT6 negative

STAT6 positive

 

Mammary Type Myofibroblastoma

Fibromatosis

Indistinct short stubby cells

Long fascicles of spindle cells

Desmin positive

Desmin negative

Loss of Rb

Rb positive

Beta catenin negative

Beta catenin positive

 

Mammary Type Myofibroblastoma

Atypical Lipomatous Tumor / Well Differentiated Liposarcoma

No atypical fat cells

Lipoblasts

CD34 and Desmin positive

CD34 and Desmin negative

Loss of Rb

Rb positive

MDM2, CDK4 negative

MDM2, CDK4 positive

Bibliography

Robert V Rouse MD
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting 3/14/16

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