Soft Tissue Pathology

1. Soft Tissue Pathology Richard Anderson, MD President, Associated Pathology Consultants, S.C. Edward Hospital & Elmhurst Memorial Hospital Clinical Instructor, Department of Pathology, UIC College of Medicine Chairman of the Board, Heartland Blood Centers UIC M2 Pathology - 2004

2. Soft Tissue • Fibrous tissue • Adipose tissue • Synovial tissue • Skeletal muscle • Blood vessels • Peripheral nerves

3. Tumors and Tumor-Like Conditions of Fibrous Tissue • Benign • Nodular Fasciitis • Palmar fibromatosis • Abdominal fibromatosis (desmoid tumor) • Malignant • Fibrosarcoma

4. Nodular Fasciitis • Self-limiting pseudosarcomatous process composed of fibroblasts and myofibroblasts • Most common lesion misdiagnosed as sarcoma • Rapidly growing, richly cellular with mitoses • Related to trauma?

5. Nodular Fasciitis • Signs/Symptoms: • Rapidly growing solitary mass lesion over 1-2 weeks often at site of previous trauma • 50% of lesions are painful • Numbness or paresthesia if compression of peripheral nerve • Age: • Young adults (20-40 years) • Sex: • M = F

6. Nodular Fasciitis • Anatomic Distribution: • May occur anywhere in the body, though predilection for upper extremities (volar surface of forearm), chest wall, back, head & neck and lower extremities • Hands and feet uncommon • Head & neck most common in children and infants

7. Nodular Fasciitis • Gross Findings: • Well-circumscribed, non-encapsulated • Most lesions small (< 2.0 cm); lesions up to 10.5 cm have been described • Divided into subcutaneous, intramuscular and fascial subtypes

8. Nodular Fasciitis • Microscopic Findings: • Proliferating fibroblasts and myofibroblasts in short irregular bundles • Reticulin stromal fibrosis • Mitotic activity • Cellular and myxoid areas • Lipid-filled macrophages and giant cells

12. Nodular Fasciitis • Ancillary Testing: • IHC • Actin – positive • Cytokeratin and S100 – negative • Prognosis/Treatment: • Benign process • Surgical excision curative

13. Palmar Fibromatosis (Dupuytren’s Contracture) • Benign fibrous tissue proliferation • More common in Northern Europeans; rare in Blacks • Genetic component? • Association with unrelated diseases and social behaviors: • Types I and II DM • Epilepsy • Alcoholism • Hypercholesterolemia • Cigarette smoking • Manual labor

14. Palmar Fibromatosis • Signs/Symptoms: • Slow growing nodule of hand progression to cord-like band with contracture of 4th or 5th digit • Age: • Older adults (20% over 65 years); rare in children • Sex: • M >>> F • Anatomic Distribution: • Palmar surface of hand (R > L) • 50% of cases bilateral

17. Plump immature fibroblasts with uniform appearance and no mitotic activity

18. Plump immature fibroblasts with uniform appearance and no mitotic activity

19. Palmar Fibromatosis • Ancillary Testing: • N/A • Treatment: • Surgical excision • Recurrence is high unless dermis and fascia are removed

22. Abdominal Fibromatosis (Abdominal Desmoid Tumor) • Locally more aggressive than superficial fibromatoses • High recurrence rate • Previous trauma • Common in patients with Gardner’s syndrome • Autosomal dominant • Colonic polyposis • Fundic gland polyps • Soft tissue and bone tumors • Estrogen?

23. Abdominal Fibromatosis • Signs/Symptoms: • Deep-seated, poorly-circumscribed firm mass in abdominal wall • Little to no pain • Age: • Young adults (20-30 years) • Sex: • F >>>>>>> M • Gravid or parous females • Anatomic Distribution: • Muscles and fascia of rectus abdominus and internal oblique

24. Abdominal Fibromatosis • Gross Findings: • Poorly-circumscribed tumors • Off-white and firm • 3-10 cm in diameter • Microscopic Findings: • Proliferating spindle cells in bundles surrounded by collagen • Limited mitoses

28. Abdominal Fibromatosis • Ancillary Testing: • N/A • Prognosis/Treatment: • Surgical excision • Recurrence rate 15-30% • Local radiation

29. Fibrosarcoma • Malignant mesenchymal tumor • Variety of microscopic appearances • Tumors arise from intramuscular and intermuscular fibrous tissue, fascia, aponeuroses or tendons

30. Fibrosarcoma • Signs/Symptoms: • Solitary palpable mass (3.0 to 8.0 cm) • Slow-growing • 1/3 of cases present with pain • Age: • Adult-type • 30-55 years • Infantile type • First 2 years of life • Congenital • Sex: • M > F

31. Fibrosarcoma • Anatomic Distribution: • Adult-type • Deep soft tissues of lower extremities • Upper extremities; head & neck • Rare organ involvement (heart, lung, liver, CNS) • Infantile-type • Distal extremities • Gross Findings: • Solitary, lobulated, circumscribed and frequently encapsulated • May invade adjacent structures

35. Cellular tumors comprised of fusiform spindle cells

36. Prominent mitotic activity; little pleomorphism; anaplastic tumor cells or giant cells are not seen

37. Fibrosarcoma • Ancillary Testing: • IHC • Vimentin – positive • Cytokeratin and S100 – negative • Actin – variable • Prognosis/Treatment: • Local recurrence rate 50% • Metastasis via bloodstream to lung and bone • 5-year survival • Adult-type: 80% for grade 1; 21% for grade 4 • Infantile-type: > 80% • Wide surgical excision, RT, chemo

38. Tumors and Tumor-Like Conditions of Fibrohistiocytic Origin • Benign: • Benign Fibrous Histiocytoma (Dermatofibroma) • Intermediate: • Dermatofibrosarcoma Protuberans (DFSP) • Malignant: • Malignant Fibrous Histiocytoma (MFH)

39. Benign Fibrous Histiocytoma • Signs/Symptoms: • Solitary slow-growing nodule of skin • Often elevated or pedunculated • 1/3 of cases multiple • Age: • Young adults to mid-adulthood (20-45 years) • Sex: • M = F • Anatomic Distribution: • Most common on distal extremities

40. Small red-brown to blue nodules

41. Poorly-circumscribed, non-encapsulated, cellular proliferation in dermis; fibroblastic cells arranged in “storiform” pattern; numerous foreign body (Touton) giant cells; Mitoses rare to absent

42. Benign Fibrous Histiocytoma • Ancillary Testing: • N/A • Prognosis/Treatment: • Simple surgical excision • < 5% recurrence

43. Dermatofibrosarcoma Protuberans • Signs/Symptoms: • Slow-growing, non-painful tumor • Antecedent trauma in 10-20% of cases • Age: • Younger than dermatofibroma • Sex: • M > F • Anatomic Distribution: • Trunk, groin and proximal extremities (as opposed to dermatofibroma)

44. Solitary masses of subcutis and skin; average size 5.0 cm

45. May lead to ulceration of overlying skin with associated hemorrhage and cystic change

46. Cellular tumors of dermis and subcutis; slender fibroblasts in monotonous storiform pattern

47. Little pleomorphism with low to moderate mitotic activity

48. Dermatofibrosarcoma Protuberans • Ancillary Testing: • IHC • CD34 – positive • Cytogenetics • Supernumerary ring structure formed by amplified sequences from chromosomes 17 and 22 • Fusion of COL1A1 and PDGF genes • Overexpression of PDGF may lead to DFSP • Prognosis/Treatment: • Locally aggressive; recurs in 50% of cases • Rarely metastasizes (<4% of cases) • Wide surgical excision; RT for large tumors or positive margins

49. Malignant Fibrous Histiocytoma • Most common sarcoma of late adult life • May occur secondary to previous RT • Signs/Symptoms: • Painless, enlarging mass if on extremity • Retroperitoneal tumors may present with obstruction and anorexia • Fever and leukocytosis • Tumor production of IL-6, IL-8 and TNF • Age: • Late adulthood (50-70 years) • Sex: • M >> F (70% of MFH in men)

50. Malignant Fibrous Histiocytoma • Anatomic Distribution: • Lower extremities (thigh), followed by upper extremities and retroperitoneum • Gross Findings: • Solitary, multilobulated fleshy masses • 5-10 cm • Two-thirds within skeletal muscle • Prominent areas of hemorrhage and necrosis