Introduction
Materials and methods
Patients and histopathology
Conventional schwannomaa
| Melanotic schwannomaa,b
| Leptomeningeal melanocytoma (MC)c
| Cellular blue nevusb
| |
---|---|---|---|---|
Localization | Majority outside central nervous system, most often skin and subcutaneous tissue | Near the neural axis (esp. spinal nerve roots, cranial nerves) or peripherally located in a wide variety of sites (soft tissue, skin, etc.) | Mostly at the cervical and thoracic spinal level, sometimes posterior fossa and supratentorial compartment | Skin (mainly dermis); frequently buttocks or sacrococcygeal region |
Origin | Nerve sheath (schwann cell) | Nerve sheath (schwann cell) | Leptomeningeal melanocyte | Dermal melanocyte |
Growth pattern, margin | Circumscribed, encapsulated | Circumscribed, often encapsulated | Circumscribed, non-encapsulated; MC with invasion of CNS is classified as intermediate-grade MC | Non-encapsulated; both infiltrative and pushing border |
Melanin pigmentation | Absent | Variably, often heavily pigmented | Variably, often heavily pigmented; can rarely be absent | Variably; can rarely be absent |
Psammoma bodies and/or fat | Absent | Present in the psammomatous form | Absent | Absent |
Schwannian featuresd
| Present | Often less pronounced than in conventional schwannoma | Absent | Degenerative changes reminiscent of ancient schwannoma can be present |
Cell phenotype | Spindle | Spindle, epithelioid | Spindle, epithelioid | Spindle, ovoid, dendritic (biphasic architecture) |
Nuclear atypia | Generally absent; ancient changes (‘degenerative atypia’) can be present | Usually mild; prominent nuclear atypia with increased mitotic activity and necrosis is indicative of aggressive behavior | Generally absent; MC with increased mitotic activity (2–5 per 10 HPF) is classified as intermediate-grade MC | Variable; absence of necrosis, mitotic activity < 2 per 2 mm2
|
S-100 | Positive | Positive | Positive | Positive |
HMB-45 and/or Melan-A | Negative | Positive | Positive | Positive |
Basement membrane staining | Pericellular pattern | Pericellular or biphasic (pericellular and nested) pattern | Nested pattern | Predominantly nested pattern |
DNA extraction
Mutational analysis
Statistical analysis
Results
Patient and histopathological characteristics
Patient | Sex | Age | Diagnosis | Localization | Origin from nerve/ganglion | Circumscribed, capsule | Pigmentation | Psammoma bodies | Cell type | Schwannian features | Nuclear pleomorphism | S-100 | HMB-45 | Melan-A | Basement membrane staining | GNAQ exon 5 mutation |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | F | 75 | MS | L1–L2 | na | + | 1+ | + | S | Pa | mi | 2+ | 1+ | 1+ | B | – |
2 | F | 35 | MS | L1–5 | + | + | 3+ | + | E, S | Pa | mi | 2+ | 1+ | 2+ | B | – |
3 | M | 42 | MS | L2 | na | + | 3+ | − | S | – | mi | 2+ | 2+ | 1+ | B | – |
4 | na | na | MS | C2 | + | + | 3+ | + | E, S | A, V | mi | 2+ | 2+ | 1+ | P | – |
5 | na | na | MS | C1 | na | na | 3+ | + | S | – | mi | 2+ | 1+ | 2+ | P | – |
6 | na | na | MS | C4 | na | na | 3+ | + | E, S | – | mi | 2+ | 2+ | 2+ | B | – |
7 | M | 35 | MS | Lumbal | + | na | 3+ | + | S | Pa | mi | 2+ | 1+ | 2+ | B | – |
8 | F | 23 | MS | Lower arm | na | + | Focal 1+ | +, fat | E | – | mi | 2+ | 1+ | 1+ | P | – |
9 | M | 13 | MS | Lower leg | + | + | Focal 1+ | + | E, S | – | mi | 2+ | 1+ | 1+ | P | – |
10 | M | 72 | Sw | Vestibular nerve | na | na | 2+ | − | S | Pa | mi | 2+ | neg | neg | P | – |
11 | F | 60 | Sw | Th11 | na | na | Focal 1+ | − | S | Pa, V | mi | 2+ | neg | neg | P | – |
12 | F | 32 | Sw | Retroperitoneum | na | + | Focal 1+ | − | S | Pa, A | mi | 2+ | neg | neg | P | – |
13 | M | 42 | Sw | sacrum | na | + | Focal 1+ | − | S | Pa | mi | 2+ | neg | neg | P | – |
14 | na | na | Sw | Intercostal nerve | na | + | 1+ | − | S | Pa, A | mi | 2+ | neg | neg | P | – |
15 | M | 49 | Sw | S1 | na | na | Focal 1+ | − | S | Pa, A | mi | 2+ | neg | neg | P | – |
16 | F | 74 | Sw | S2 | + | na | Focal 1+ | − | S | Pa | mi | 2+ | neg | neg | P | – |
17 | F | 74 | Sw | Groin | na | na | Focal 1+ | − | S | Pa, A | mi | 2+ | neg | neg | P | – |
18 | M | 44 | Sw | Sacral | na | + | Focal 1+ | − | S | Pa, A | mi | 2+ | neg | neg | P | – |
19 | na | na | Blue nevus | Foot | na | + | 2+ | − | S, O | – | mi | Focal 1+ | 2+ | Focal 1+ | N | c626A>T, pGln209Leu |
20 | na | na | IMC | Cauda | na | No, invasion of CNS | 1+ | − | S | – | mi | Focal 1+ | 2+ | 2+ | N | c626A>T, pGln209Leu |
21 | na | na | IMC | IM | na | No, invasion of CNS | 3+ | − | E, S | – | mi | Focal 1+ | 2+ | 1+ | N | – |
22 | na | na | IMC | IM | na | No, invasion of CNS | 1+ | − | E | – | mi | Focal 1+ | 2+ | 1+ | N | c626A>T, pGln209Leu |
23 | na | na | MC | EM | na | na | 3+ | − | E | – | mi | Focal 1+ | 2+ | 1+ | N | c626A>T, pGln209Leu |
24 | F | 41 | NOS | L5 | + | na | 3+ | − | E, S | – | mo sev | 1+ | 1+ | 2+ | B | − |
25 | na | na | NOS | CPA | na | na | 3+ | − | S | – | mi | Focal 1+ | 2+ | 1+ | N | c626A>T, pGln209Leu |