• Uncommon benign tumor of peripheral nerve composed primarily of perineurial cells, first described in 1978
• Adults, more common in females
• Extremities and trunk most common sites

• 23 year old man with median nerve tumor (Hand (N Y) 2010;5:286)
• 30 year old man with thigh mass and neurofibromatosis 2 (Am J Surg Pathol 2006;30:1624)
• 53 year old woman with endobronchial tumor (Patholog Res Int 2010;2010:613824)
• 63 year old man with retroperitoneal mass (J Med Case Rep 2010;4:290)

Endobronchial nodule

Finger

Mouth

• Well circumscribed, variable size, usually NOT associated with a nerve

• Bland, elongated cells in parallel bundles, resembles neurofibroma or pacinian neurofibroma; may have storiform growth
• May have collagenous stroma with pericellular cracking / clefting
• No atypia, rare mitotic figures
• Suspect if myxoid lesion of soft tissue with storiform or fascicular growth pattern

Median nerve

Retroperitoneum

Site unknown

Endobronchial nodule in 53 year old woman

• EMA, CD34 (33%)

• S100

• Non-branching, thin cytoplasmic processes, coated by external lamina, joined at ends by tight junctions, few organelles, actin and vimentin filaments, numerous pinocytotic vesicles

• Monosomy 22, deletion of 22q11-13.1

• Median age 43, range 34-61, 2/3 women in small study
• Upper extremity, gingiva, inguinal region
• Appears to have benign behavior

• 52 year old woman with swelling in neck (Head Neck 2009;31:833)

• Median 4 cm, range 1.5 to 10 cm

• Lace-like or reticular ("net-like") growth pattern of anastomosing cords of fusiform cells with bipolar cytoplasmic processes and pale eosinophilic cytoplasm
• Central nuclei
• Commonly ransitions to more cellular areas (Am J Surg Pathol 2001;25:485)
• Collagenous to myxoid stroma
• Cystic areas common
• No mitotic figures
• Mild/moderate nuclear atypia (may be degenerative)

Stomach tumor

• EMA, Alcian blue (myxoid stroma)

• S100

• Extraskeletal myxoid chondrosarcoma: deep seated tumor, subfascial or intramuscular, cord/lace like architecture, larger cells with abundant eosinophilic cytoplasm, no microcystic change, typical t(9;22)
• Myoepithelial tumors: variable S100+, keratin; acinar or ductal component
• Myxoid synovial sarcoma: deep soft tissue, younger age group, more nuclear atypia, EMA+, CK+, CD99+, bcl2+

• Usually small tumors in dermis of hands

• 16 year old girl with nodule in palmar region (An Bras Dermatol 2009;84:643)
• 17 year old boy with painless nodule in buccal mucosa (Head Neck Pathol 2010;4:169)

Palmar region

Various images

Buccal mucosa of 17 year old boy

Left palmar region of 16 year old girl

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