Diagnosis

Most common GI location

Characteristics

Positive immunohistochemistry markers

Mutations

Gastrointestinal Stromal Tumor (GIST)

Any

Uniform pattern: spindle and epithelioid cells

CD117, DOG1, S100 (spindle 5.3%), Melan-A

c-KIT, PDGFR-α

Melanoma

Small Intestine, Anus

Pleomorphism, mitosis, intranuclear inclusions

S100, HMB45, Melan-A, CD117 (63%)

BRAF

Primary Clear Cell Sarcoma of the Gastrointestinal Tract

Small Intestine

Mostly epithelioid, prominent nucleoli, mitosis

S100 and negativity for HMB45 and Melan-A

t(12; 22) (q34; q12) EWS-CREB1 Fusion gene, t(12; 22) (q13; q12) EWS-ATF1 Fusion gene

Leiomyoma/sarcoma

Esophagus

Spindle cells with blunt tips

Smooth muscle actin, Desmin

No

Schwannoma

Rare

In the muscularis propria, lymphoid infiltrate

S100

No

Solitary Fibrous Tumor

Colon

Spindle cell, hemangiopericytic pattern

CD34, BCL-2

No

Fibromatosis

Mesenteric

Spindle, focal atypia

B-catenin

No

Inflammatory Fibroid Polyp

Submucosal inflammation, no atypia or mitosis

CD34

PDGFR-α