Spindle Cell Tumours Of adults

Question 1

Nonmesenchymal Spindle Cell Neoplasms

Answer 1

Spindle cell carcinoma (sarcomatoid carcinoma, spindle cell SCC)
Spindle cell/desmoplastic melanoma
Spindle cell/desmoplastic mesothelioma

Paraganglioma
Gliosarcoma (metastasis)
Extracranial meningioma
Myeloid sarcoma (extramedullary myeloid tumor)
Interdigitating dendritic cell sarcoma
Mast cell neoplasms (systemic mastocytosis, mastocytoma, mast cell sarcoma)

Question 2

Preferential location of pseudosarcomatous myofibroblastic proliferation

Answer 2

urinary tract

Question 3

preferential location of intranodal palisaded myofibroblastoma

Answer 3

inguinal lymph nodes

Question 4

Preferential location fibroma of tendon sheath

Answer 4

hand and foot

Question 5

Preferential location nuchal fibroma

Answer 5

back of neck

Question 6

Preferential location elastofibroma

Answer 6

scapular area

Question 7

Preferential location solitary circumscribed neuroma

Answer 7

face

Question 8

Preferential location spindle cell lipoma

Answer 8

upperback, shoulder, neck

Question 9

Preferential location superficial fibromatoses

Answer 9

palmar, plantar, and penile areas

Question 10

Preferential location GIST

Answer 10

intraabdominal

Question 11

Preferential location dedifferentiated liposarcoma

Answer 11

retroperitoneum, paratesticular

Question 12

Preferential location spindle cell angiosarcoma

Answer 12

head and neck - especially face and scalp

Question 13

Preferential location spindle cell rhabdomyosarcoma

Answer 13

paratesticular, head and neck

Question 14

Preferential location biphenotypic sinonasal sarcoma

Answer 14

nasal cavity and paranasal sinuses

Question 15

Mesenchymal spindle cell tumours

Answer 15

nodular fasciitis

pseudosarcomatous myofibroblastic proliferation

Question 16

Nodular fasciitis

Patient age:
PMHx
Anatomic location / tumour depth:

Histologic parameters
Architecture / Growth pattern:
ECM:
Intratumoural vascularity:
Tumour necrosis:
Cytomorphology: shape, cytoplasm, nuclear features, atypia
Mitotic activity:
Ancillary technique:

Prognosis

DDs:

Answer 16

Key points:

• rapid growth
• young to middle age
• forearm, head and neck
• rare in skin, joints, and blood vessels
• initially highly cellular then hypocellular and fibrotic
• myxoid stroma, extravasated RBC, tissue culture-like

Patient age: 20-40yo, no gender predilection
PMHx: 10-20% trauma, painful, develops rapidly over 4-8 weeks.

Anatomic location / tumour depth: wide, but mostly upper extremities 50%, head neck in children, infrequent in hand and feet, 10% intramusclular, but intraarticular, intravascular, intradermal, parosteal, cranial.

Histologic parameters
Architecture / Growth pattern: well circumscribed, less than 3cm,

In the subcutis, grow along fibrous septa, dissecting the adipose tissue, center around superficial aponeurosis. Variably cellular, consisting of fibroblasts and myofibroblasts arranged in short irregular fasciles, sometimes vague storiform pattern, loose textured myxoid matrix (feathery patters) or collagenous stroma.

centre of lesion can be hypocellular, giving zonal appearance,

Long standing lesions are less cellular, and more fibrotic, hyalinised fibrosis arranged in dense, refractile, keloid -like collagen bands

10% cases contain prominent osteoclast-like MNGC.

ECM: loose myxoid or collagenous, surrounded by inflammatory elements, mucin pooling, cystic change, interstitial haemorrhage, intralesional histiocytes are common.

Intratumoural vascularity: centripetally oriented capillaries.

Tumour necrosis: no

Cytomorphology: shape, cytoplasm, nuclear features,

Plump abundant eosinophilic fibrillary cytoplasm, resembling cells in tissue culture or granulation tissue.

Nuclei: vesicular, single and often prominent

Mitotic activity: numerous and typical

Ancillary technique:
myofibroblasts are strongly and diffusely positive for smooth muscle actin, muscle specific actin (clone HHF35), and calponin.

Negative for:
Desmin is observed in a few scattered cells
caldesmon, s100, cd34, beta-catenin

visceral lesion are positive for keratins,
histiocytes and osteoclast like giant cells CD68 and other histiocyte markers

Ki67- high proliferative activity

ganglion-like cells are negative for muscle markers.

molecular: clonal proliferation - rearrangements of USP6 locus at 17p13 in 90% of cases, MYH9-USP6 gene fusion detected in 65% of cases, resulting in overexpression of USP6 oncoprotein, similar to aneurysmal bone cyst.

DD - sarcomas, but NF grow fast, small, subcut, no enlarged or hyperchromatic nuclei, no necrosis, atypical mitotic figures.

myxofibrosarc - usually older, multinodular, alternating cellular and myxoid areas, enlarged hyperchromatic nuclei

DFSP - positive for CD34, neg for SMA

MPNST positive for s100, GFAP, sox 10,

LG fibromyxoid sarc - positive for MUC4, EMA and neg for SMA

Prognosis: benign, self-limiting. Local recurrences rare. Spont regression can occur.