Soft Tissue Tumors Part 1
Introduction, Fibrous, Fibrohistiocytic and Adipose tumors
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Last revised 23 May 2008
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Triphasic pattern seen in Fibrous Hamartoma of Infancy
Table of Contents for Soft Tissue Tumors Part 1
Introduction: primary references, soft tissue-normal, approach to diagnosis, sarcomas-general, syndromes, grading, cell types, architectural patterns, molecular
Infections, inflammation and hematoma: general, granulomatous, hematoma, necrotizing fasciitis, PVP granuloma, tumoral calcinosis
Fibroblastic/myofibroblastic: normal, general, angiomyofibroblastoma, calcifying aponeurotic fibroma, calcifying fibrous tumor, cellular angiofibroma, dermatofibrosarcoma protuberans, desmoplastic fibroblastoma, elastofibroma, eosinophilic fasciitis, fibroma of tendon sheath, fibromatosis-general, fibromatosis-superficial, fibromatosis-deep, fibromatosis colli, fibrosarcoma-adult, fibrosarcoma-infantile, fibrous hamartoma of infancy, focal myositis, Gardner fibroma, giant cell angiofibroma, giant cell fibroblastoma, hemangiopericytoma, inclusion body fibromatosis, inflammatory myofibroblastic tumor, ischemic fasciitis, juvenile hyaline fibromatosis, lipofibromatosis, low grade fibromyxoid sarcoma, low grade myofibroblastic sarcoma, mammary type myofibroblastoma, myofibroma / myofibromatosis, myositis ossificans, myxofibrosarcoma, myxoinflammatory fibroblastic sarcoma, nodular fasciitis and related lesions, nuchal fibrocartilaginous pseudotumor, nuchal type fibroma, ossifying fibromyxoid tumor, pleomorphic fibroma, proliferative fasciitis, proliferative myositis, proliferative peribursitis, sclerosing epithelioid fibrosarcoma, solitary fibrous tumor, superficial acral fibromyxoma
Fibrohistiocytic: general, atypical fibrous histiocytoma, atypical fibroxanthoma, benign fibrous histiocytoma (superficial), deep benign fibrous histiocytoma, giant cell tumor of soft tissue, giant cell tumor of tendon sheath-diffuse, giant cell tumor of tendon sheath-localized, MFH-giant cell, MFH-inflammatory, MFH-pleomorphic, pleomorphic hyalinizing angiectatic tumor, plexiform fibrohistiocytic tumor
Adipose tissue-benign: embryology & physiology, white fat , brown fat
lipoma and variants: lipoma, angiolipoma, chondroid, fibrolipoma, intramuscular, lipoma arborescens, lipoma of tendon sheath, lipomatosis, lipomatosis of nerve, lumbosacral, myelolipoma, myolipoma, myxoid, nevus lipomatosus, pelvic, pleomorphic/spindle cell
other benign lesions: hemosiderotic fibrohistiocytic lipomatous lesion, hibernoma, lipoblastoma, subconjunctival herniated orbital fat
Adipose tissue-liposarcoma: general, atypical lipomatous tumor/well differentiated, dedifferentiated, myxoid, pleomorphic, mixed type, sclerosing poorly differentiated
Go to Soft Tissue Tumors Part 2 - Muscle, Vascular, Nerve, Other
Primary references - Soft tissue tumors Part 1
American Journal of Clinical Pathology (AJCP) [free full text and no registration after 1 year], January 2000 to May 2008
American Journal of Surgical Pathology (AJSP), January 2000 to May 2008
Archives of Pathology and Laboratory Medicine (Archives) [always free full text and no registration]; January 1999 to May 2008
Biomed Central [always free full text and no registration]; 24 July 2001 to 1 May 2008
Human Pathology (Hum Path), January 2000 to May 2008
Modern Pathology (Mod Path) [free full text and no registration after 1 year]; Jan 2000 to May 2008
Fletcher: Pathology and Genetics of Tumours of Soft Tissue and Bone (AFIP 3rd Series, Vol 30), 2004
Fletcher:
Pathology and Genetics of Tumours of Soft Tissue and Bone (WHO, Vol 5), Chapter 1-adipocytic
tumors, Chapter
2-fibroblastic/myofibroblastic tumors, Chapter 3-fibrohistiocytic
tumors
Rosai,
J: Ackerman’s Surgical Pathology (9th Ed, 2004)
Sternberg, S: Diagnostic Surgical Pathology (4th Ed, 2004)
Websites with images: PathoPic, PEIR digital library; virtual slides - ASCP, OSU, USCAP
Journal search terms: each disease entity listed
Please refer to these primary references for more detailed discussions and photographs
Definition: nonepithelial extraskeletal tissue, excluding supportive tissue of organs and lymphoid/hematopoietic tissue
Includes fibrous tissue, adipose tissue, skeletal muscle, blood vessels, lymphatics and peripheral nervous system
Usually mesodermal in origin; peripheral nerves derive from neuroectoderm
Soft tissue tumors - approach to diagnosis
Modified from Sternberg
1) Is lesion reactive or neoplastic?
2) Is lesion malignant? (necrosis favors malignancy)
3) Is malignant lesion a sarcoma? (may be melanoma, carcinoma, lymphoma)
4) What type of differentiation is present? - assign to phenotypic category or classify as round cell, spindle cell, epithelioid, other
7,000/year in US
Classified based on type of cellular differentiation, although most arise not from differentiated cells, but from multipotent mesenchymal cells that then differentiate along various cell lines
Diagnostic errors are often due to lack of familiarity with rare lesions, not failure to perform immunostains (AJCP 2001;116:473)
WHO classification: last revised in 2002 - Histopathology 2006;48:3, classification
Recommended to diagnose with FNA or incisional biopsy so appropriate treatment can be determined in advance
Congenital soft tissue tumors, even with high grade features, rarely have malignant behavior
Nodal involvement uncommon
Local recurrences show increased number of genetic changes, including loss at 9p, gains at 5p and 20q (Mod Path 2001;14:978)
Usually arise de novo, not from benign tumors (MPNST may be an exception); do not appear to arise from trauma
May be caused by radiation therapy (MFH, extraskeletal osteosarcoma) or foreign bodies (MFH, angiosarcoma)
Poor prognostic factors: large size, deep seated versus superficial, retroperitoneum versus extremities, high grade, high stage, positive margins (associated with local recurrence)
Treatment: enucleation acceptable only for schwannomas; for other small tumors, must excise with 1-2 cm rim of normal tissue; surgery should also remove site of prior FNA or incision
Wide local excision for infiltrative lesions (fibromatosis, DFSP); amputation is less commonly performed now than in the past
Radiation and chemotherapy may also be used
Surgical resection of pulmonary metastases often has value
Fine needle aspiration: most specimens are recognized as sarcoma, and subtyping is most accurate in bone sarcomas and pediatric sarcomas; subtyping is often not possible in adult specimens, but this usually does not affect initial therapy (AJCP 2001;115:59)
Staging is discussed in Soft Tissue Tumors - Part 2 (click here)
Syndromes (molecular / genetic) associated with soft tissue tumors
Bannayan Zonana syndrome: OMIM #153480, multiple lipomas and hemangiomas
Beckwith-Wiedemann syndrome: OMIM #130650, congenital overgrowth syndrome associated with alveolar rhabdomyosarcoma (Pediatr Dev Pathol 2001;4:550)
Carney syndrome / complex: autosomal dominant multiple neoplasia syndrome with myxomas and pigmented lesions of skin and mucosa, due to mutation in PRKAR1A gene (OMIM #160980) or 2p16 abnormalities (OMIM #605244)
Carney triad: OMIM # 604287, gastric leiomyosarcoma, pulmonary chondroma and extra-adrenal paraganglioma
Gardner syndrome: OMIM #175100, fibromatosis and familial adenomatous polyposis
Kasabach-Merritt syndrome: OMIM #141000, microangiopathic hemolytic anemia associated with childhood hemangioma
Klippel-Trenaunay-Weber syndrome: OMIM #149000, hemangiomas with hypertrophy of associated bone and soft tissue
Li Fraumeni syndrome: OMIM #151623, various soft tissue sarcomas, osteosarcoma, breast cancer, brain tumors, leukemia and adrenocortical carcinoma
Lipomatosis, multiple syndrome: OMIM #151800
Maffucci syndrome: OMIM #166000, hemangiomas, enchondroma, chondrosarcoma
Mazabraud's syndrome: fibrous dysplasia and intramuscular myxoma (eMedicine)
McCune-Albright syndrome: OMIM #174800, myxomas are minor feature (see Mazabraud’s syndrome), major features are polyostotic fibrous dysplasia cafe-au-lait skin pigmentation and precocious puberty
Multiple endocrine neoplasia 1: OMIM #131100, multiple lipomas may be a minor feature
Neurofibromatosis type 1: OMIM #162200, neurofibroma, MPNST
Neurofibromatosis type 2: OMIM #101000, schwannoma, neurofibroma, meningioma, astrocytoma, rarely perineurioma (AJSP 2006;30:1624)
Osler-Weber-Rendu syndrome: OMIM #187300, telangiectasias
Sturge-Weber syndrome: OMIM #185300, port-wine spot of face
Turner syndrome: cystic hygroma (eMedicine)
Grading of sarcomas of soft tissue
Indicate in pathology report which grading system is used
Grade is most important prognostic factor and indicator of metastatic risk in adults (Archives 2006;130:1448)
Grading is currently not considered appropriate for needle biopsies
Two grade systems - low grade and high grade
Low grade: usually has limited ability to metastasize
High grade: cellular with mitotic figures and necrosis, but must evaluate in context of tumor type, age and location; for example: superficial high grade MFH is unlikely to metastasize, but deep low grade MPNST is likely to metastasize
Necrosis usually signifies high grade unless tumor is well differentiated and lacks pleomorphism
Grading systems - French Federation of Cancer Centers Sarcoma Group
Grade 1: total score of 2-3
Grade 2: total score of 4-5
Grade 3: total score of 6-8
Tumor differentiation:
1 point: resembles normal adult mesenchymal tissue, may be confused with a benign lesion, such as well differentiated liposarcoma
2 points: histologic typing is certain, such as myxoid liposarcoma
3 points: synovial sarcoma, osteosarcoma, Ewing’s sarcoma/PNET, sarcomas of doubtful tumor type, embryonal and undifferentiated sarcomas
Mitotic count (count 10 successive high power fields [0.17 mm squared] in most mitotically active areas):
1 point: 0-9 mitoses
2 points: 10-19 mitoses
3 points: 20 or more mitoses
Tumor necrosis:
0 points: no necrosis on any slides
1 point: less than 50% necrosis for all examined tumor surface
2 points: tumor necrosis of 50% or more of examined tumor surface
Grading systems - French Federation of Cancer Centers Sarcoma Group - grades of common sarcoma types:
Angiosarcoma-poorly differentiated/epithelioid - 3
Angiosarcoma-well differentiated/conventional - 2
Chondrosarcoma-mesenchymal - 3
Clear cell sarcoma - 3
Epithelioid sarcoma - 3
Fibrosarcoma-conventional - 2
Fibrosarcoma-well differentiated - 1
Fibrosarcoma-poorly differentiated - 3
Leiomyosarcoma-conventional - 2
Leiomyosarcoma-epithelioid / poorly differentiated / pleomorphic - 3
Leiomyosarcoma-well differentiated - 1
Liposarcoma-myxoid - 2
Liposarcoma-pleomorphic - 3
Liposarcoma-round cell - 3
Liposarcoma-well differentiated - 1
Malignant triton tumor - 3
MFH-giant cell - 3
MFH-pleomorphic with storiform pattern - 2
MFH-pleomorphic without storiform pattern - 3
Myxofibrosarcoma - 2
Osteosarcoma - 3
PNET - 3
Rhabdomyosarcoma-alveolar / embryonal / pleomorphic - 3
Synovial sarcoma - 3
Grading systems of soft tissue tumors - National Cancer Institute (US) tumor grading system
Grade 1: well differentiated liposarcoma, myxoid liposarcoma (grade 2 in French system above), subcutaneous myxoid MFH; well differentiated malignant hemangiopericytoma with < 1 MF/10 HPF, no necrosis and no hemorrhagic areas; well differentiated fibrosarcoma with orderly herringbone pattern or well differentiated leiomyosarcoma with orderly fascicular pattern plus well differentiated cytologic features, no pleomorphism, no necrosis, < 6 MF/10 HPF; malignant schwannoma (MPNST) if resembles neurofibroma plus mitotic figures plus areas of high cellularity but < 6 MF/10 HPF; myxoid chondrosarcoma that is uniformly myxoid and hypocellular with no mitotic activity
Grade 3: extraskeletal Ewing’s sarcoma, PNET, extraskeletal osteosarcoma, mesenchymal chondrosarcoma, malignant triton tumor, or other histologic types with 15% or more necrosis
Grade 2: other histologic types with <15% necrosis
References: J Clin Oncol 1997;15:350, J Surg Oncol 1989;41:263
Cell types for soft tissue tumors
Epithelioid: alveolar soft parts sarcoma, carcinomas (extension into soft tissue or metastases), epithelioid sarcoma, rhabdoid tumors, synovial sarcoma; epithelioid variants of leiomyosarcoma, MPNST or vascular tumors
Pleomorphic: variants of leiomyosarcoma, liposarcoma, MFH, MPNST or rhabdomyosarcoma; also melanoma and metastatic carcinoma
Round cell: desmoplastic small round cell sarcoma, Ewings/PNET, mesenchymal chondrosarcoma, rhabdomyosarcoma, round cell liposarcoma; also carcinoma, lymphoma, melanoma, neuroblastoma
Spindle cell: benign nerve sheath tumor, DFSP, fibroma of tendon sheath (cellular), fibromatosis, fibrosarcoma, leiomyosarcoma and leiomyoma, MPNST, nodular fasciitis, spindle cell variant of embryonal rhabdomyosarcoma, synovial sarcoma
Architectural patterns of soft tissue tumors
Alveolar: alveolar rhabdomyosarcoma, alveolar soft parts sarcoma
Fascicular: fibromatosis, fibrosarcoma, neural tumors (benign or malignant), smooth muscle tumors, synovial sarcoma
Glandular: adenocarcinoma, biphasic synovial sarcoma, glandular MPNST
Lobular: clear cell sarcoma, epithelioid sarcoma, myxoid chondrosarcoma
Palisading: Schwann cells (neural tumors), smooth muscle tumors, spindle cell lipoma
Plexiform: nerve sheath tumors, plexiform fibrous histiocytoma
Plexiform vascular: myxofibrosarcoma, myxoid liposarcoma, nodular fasciitis
Storiform: fibrohistiocytic tumors, dedifferentiated liposarcoma, low grade fibromyxoid sarcoma, perineurioma,
Molecular / cytogenetics of soft tissue tumors
RT-PCR or FISH of paraffin-embedded tissue for tumor fusion transcripts is useful (AJSP 2002;26:965, AJSP 2008;32:8)
Note: in table below, gene for first chromosome in translocation is listed first
Alveolar soft parts sarcoma: t(X;17)(p11.2;q25) - ASPL-TFE3 fusion gene
Angiomatoid fibrous histiocytoma: t(12;16)(q13;p11) - FUS-ATF1 fusion gene or t(12;22)(q13;q12) - FUS-EWS fusion gene
Chondrosarcoma, myxoid, extraskeletal: t(9;22)(q22;q12) - CHN-EWS fusion gene
t(9;15)(q22;q21) - CHN-TCF12 fusion gene
t(9;17)(q22;q11) - CHN-RBP56 fusion gene
Clear cell sarcoma: t(12;22)(q13;q12) - ATF1-EWS fusion gene
Congenital fibrosarcoma / mesoblastic nephroma: t(12;15)(p13;q25) - ETV6-NTRK3 fusion gene
Dermatofibrosarcoma protuberans / giant cell fibroblastoma: t(17;22)(q22;q13) - COL1A1-PDGFB fusion gene
Desmoplastic small round cell tumor: t(11;22)(p13;q12) - WT1-EWS or t(21;22)(q22;q12) - ERG-EWS fusion genes
Ewing’s sarcoma/PNET, extraosseous: t(11;22)(q24;q12) - FLI1-EWS fusion gene
t(21;22)(q22;q12) - ERG-EWS fusion gene
t(2;22)(q33;q12) - FEV-EWS fusion gene
t(7,22);(p22;q12) - ETV1-EWS fusion gene
t(17;22)(q12;q12) - E1AF-EWS fusion gene
Inflammatory myofibroblastic tumor: translocations at 2p23 involving ALK gene
Lipoma: t(12;14)(q13-15;q23-24) or related changes involving HMGA2/HMGIC at 12q13-15
Liposarcoma-myxoid/round cell variants: t(12;16)(q13;p11) - TLS-CHOP/FUS fusion gene or t(12;22)(q13;q12) - CHOP-EWS fusion gene
Liposarcoma, well differentiated: marker ring or giant chromosomes derived from 12q13-15
Low grade fibromyxoid sarcoma: t(7;16)(q32-34;p11) - FUS-CREB3L2 or t(11;16)(p11;p11) - FUS-CREB3L1
Rhabdomyosarcoma, alveolar: t(2;13)(q35;q14) - PAX3-FKHR or t(1;13)(p36;q14) - PAX7-FKHR
Synovial sarcoma: t(X;18)(p11.23;q11) - SYT-SSX1 or t(X;18)(p11.21;q11) - SYT-SSX2 fusion genes
Tenosynovial giant cell tumor: t(1;2)(p11;q35-37)
References: Archives 2006;130:1199
Infections, inflammation and hematomas of Soft Tissue
Infections of Soft Tissue - general
Usually due to direct extension from infections of skin, bone or viscera, or due to trauma or surgery
Granulomatous infections of soft tissue
Due to tuberculosis, fungi, atypical mycobacteria (Clin Infect Dis 1995;21:65, Int J Tuberc Lung Dis 2007;11:96)
Case reports: Brucella gluteal abscess in Turkey (Intern Med 2008;47:171)
May clinically resemble a tumor if deep seated
Usually near tensor fascia lata (upper thigh muscle, image)
Case reports: in tensor fascia lata (Dermatol Online J 2001;7:6), giant chronic expanding hematoma of thigh (Joint Bone Spine 2008;75:64), mass of thorax (Yonsei Med J 2007;48:337)
Treatment: complete surgical excision, including pseudocapsule
Necrotizing fasciitis of soft tissue
Definition: uncommon fulminant soft tissue infection characterized by extensive fascial necrosis
Fatal if untreated
Particularly serious in patients with badly controlled diabetes (Diabetes Res Clin Pract 2008;80:218)
Usually due to group A streptococci, also community-acquired MRSA (Surg Infect (Larchmt) 2008 Apr 9 [Epub ahead of print])
Case reports: due to Pseudomonas (Intern Med 2008;47:553)
Treatment: start promptly to minimize morbidity (World J Emerg Surg 2007;2:19)
References: eMedicine #1; #2
PVP granuloma
Definition: granuloma due to injection of drugs containing polyvinylpyrrolidone (PVP)
Micro: focal cellularity, focally myxoid with foamy histiocytes containing vacuoles and PVP
Positive stains (histiocytes): mucicarmine, colloidal iron, GMS, Congo Red, Sudan Black B
DD: myxoid liposarcoma, signet ring carcinoma
Tumoral calcinosis
Definition: large painless calcified masses in periarticular soft tissues, including elbows, hips, only rarely knees
Autosomal dominant
Local recurrence common
Elevated serum calcium, hyperphosphatemia, elevated serum Vitamin D levels
Xray: lobulated calcifications, separate from associated bone
Gross: large, multinodular, chalky masses
Fibroblastic / myofibroblastic tumors of soft tissue
Fibrous tissue consists of fibroblasts and extracellular matrix
Extracellular matrix consists of collagen, elastin and ground substance
Fibrous tissue: loose or dense; dense fibrous tissue includes tendons (connect muscle to bone), ligaments (connect bones or cartilage to each other), aponeuroses (ribbon like tendinous expansion)
Fibroblasts: spindled (along collagen fibers) to stellate (star shaped-in myxoid areas); produce various collagens; positive for vimentin, actin
Fibrocytes: quiescent stage of fibroblasts
Myofibroblasts: modified fibroblasts with multiple possible origins (diagram), including transition from fibroblasts during tissue repair (J Invest Dermatol 2007;127:526); features are intermediate between fibroblasts and smooth muscle cells
References: Wikipedia-fibroblasts, Wikipedia-myofibroblasts, Am J Pathol 2007;170:1807
Fibroblastic / myofibroblastic tumors of soft tissue - general
Large subset of mesenchymal tumors
Cells / tumors may have both fibroblastic and myofibroblastic features
Angiomyofibroblastoma of soft tissue
Definition: benign, well-circumscribed myofibroblastic tumor, usually in vulva
May overlap with cellular angiofibroma
First described in 1992 (AJSP 1992;16:373)
Uncommon slow growing painless mass, usually females of reproductive age
Usually vulvar, 10-15% in vagina; also scrotum or paratesticular soft tissue in men (median age 57 years)
Case reports: recurrence in vagina (Eur J Gynaecol Oncol 2007;28:324), pedunculated vulvar mass (Acta Med Okayama 2006;60:237), sarcomatous transformation in vulva (AJSP 1997;21:1104), scrotal mass, 27 year old man with tumor of inguinal region (Archives 2000;124:1679)
Treatment: excision, only rarely recurs, does not metastasize
Gross: well circumscribed but not encapsulated, usually 5-7 cm or less, tan-pink soft cut surface, no necrosis
Micro: thin fibrous pseudocapsule, alternating hyper- and hypocellular areas with prominent thin walled and ectatic vessel in edematous stroma; round to spindled tumor cells concentrated around vessels, with eosinophilic cytoplasm and often bi- or multi-nucleation; mast cells common; may have plasmacytoid or epithelioid morphology, or rarely show degenerative changes; 10% have mature adipose tissue; no/rare mitotic figures, no/rare red blood cell extravasation, no atypia; post-menopausal patients have less cellularity, less edema but more fibrosis and vessel wall hyalinization
Positive stains: vimentin, desmin (strong and diffuse, may be reduced in post-menopausal patients), ER, PgR, smooth muscle or pan-muscle actin (focal, Hum Path 1997;28:1046), occasional CD34
Negative stains: S100, keratin
EM: myofibroblastic and fibroblastic features
DD: aggressive angiomyxoma (not circumscribed, less cellular, less vascular, stromal mucin and RBC extravasation are present, infrequent plump stromal cells)
Reference: Mod Path 1996;9:284, Stanford School of Medicine
Calcifying aponeurotic fibroma of soft tissue
Definition: rare, slow growing, painless tumor with fibroblasts palisading around chondroid or calcified nodules, usually in hands and feet of children or young adults
Also called juvenile aponeurotic fibroma
50% recur, especially in children; does not metastasize
May be cartilaginous analog of fibromatosis
Case reports: Case of the Week #47, 36 year old woman with distal phalangeal bone involvement (Korean J Radiol 2008;9:91)
Treatment: conservative excision with reexcision as necessary for recurrences
Gross: nodular or infiltrative gray-white, gritty mass in subcutaneous tissue or tendon, may be calcified, usually 3 cm or less in hands or feet, may be larger elsewhere
Micro: nodules of plump or epithelioid fibroblasts palisading around cartilage and spotty calcification; cells have indistinct and variable cytoplasm, plump oval nuclei with vesicular chromatin that may be condensed below nuclear membrane; fibrocytes in stroma between nodules have dense, evenly dispersed chromatin; may infiltrate fat or striated muscle at periphery; frequent osteoclast-like giant cells; rare mitotic figures, no atypia; more cellular in very young
Cytology: benign appearing spindle cells, chondroid cells, multinucleated giant cells and calcified debris (Diagn Cytopathol 2001;24:336)
Positive stains: vimentin, CD68, CD99, S100, muscle specific actin (50%), smooth muscle actin (50%) ]
Negative stains (usually): CD34, CD57, progesterone receptor
EM: chondrocytes, fibroblasts and occasional myofibroblasts
Molecular/cytogenetics: benign, but may be aneuploid (Cancer 1994;73:1200)
DD: fibromatosis (usually involves head, neck and proximal extremities in infants, not hands and feet of children/young adults, background is more myxoid than chondroid, calcification is rare; in older patients, fibromatosis usually lacks calcification or chondroid differentiation), chondroma of soft parts (may involve hands, but usually well circumscribed with more well developed chondroid differentiation, no infiltration of adjacent tissue), fibrous hamartoma of infancy (immature mesenchyme, fibroblasts are arranged in trabeculae, no cartilage or calcification, not hands and feet)
References: Hum Path 1998;29:1504, Acta Orthop Belg 2001;67:412, Stanford University
Calcifying fibrous tumor of soft tissue
Definition: benign fibrous lesion with abundant hyalinized collagen, psammomatous or dystrophic calcifications and lymphocytic infiltration
Also called calcifying fibrous pseudotumor
First described in 1993 (AJSP 1993;17:502)
Adolescents/young adults, all sites
Unrelated to inflammatory myofibroblastic tumor, based on histology and immunoreactivity (Mod Path 2001;14:784, Int J Surg Pathol 2002;10:189)
Case reports: 24 year old woman with neck mass (Archives 2000;124:435), tumor of small intestine (Ann Diagn Pathol 2008;12:138), multiple peritoneal tumors #1 (Ann Diagn Pathol 2007;11:460), #2-familial (AJCP 2003;119:811), multiple pleural tumors (Virchows Arch 2005;446:78)
Treatment: excision, rarely recurs
Gross: well circumscribed but unencapsulated, variable size, may infiltrate into surrounding tissue, may have gritty cut surface
Micro: paucicellular fibroblastic proliferation with lymphocytes (possibly lymphoid follicles), plasma cells, eosinophils, mast cells, dense collagenous tissue, varying degrees of calcification; border is often at least partially infiltrative
Positive stains: Factor XIIIa, vimentin
Negative stains: smooth muscle actin, muscle specific actin, ALK, desmin, S100, keratin
EM: immature fibroblastic cells, collagen fibrils, dystrophic and psammatous calcifications
DD: inflammatory myofibroblastic tumor (more cellular, no calcifications, ALK+, actin+), desmoplastic fibroblastoma (older patients, low cellularity, larger prominent fibroblasts, no microcalcifications, no prominent inflammatory infiltrate), calcifying aponeurotic fibroma (more cellular, usually distal location, usually smaller lesion)
References: Stanford University
Cellular angiofibroma of soft tissue
Definition: benign, highly cellular tumor of vulva and scrotum/inguinal region with prominent blood vessels
First described in 1997 (AJSP 1997;21:636); may be related to angiomyofibroblastoma and spindle cell lipoma
In women, may arise from hormone receptor positive mesenchymal cells in lower female genital tract (Histopathology 2004;45:360)
Rare; usually ages 40+ years
Extragenital cases have similar features (APMIS 2007;115:254)
Case reports: 51 year old woman with coexisting Bartholin’s cyst (Sao Paulo Med J 2005;123:250), recurrent tumor (J Clin Pathol 2002;55:477)
Treatment: excision with negative margins; usually does not recur (AJSP 2004;28:1426)
Gross: vulvar lesions are usually up to 3 cm, male lesions may reach 14 cm; well circumscribed nodules with soft to rubbery, gray-pink-brown cut surface
Micro: well circumscribed, variable pseudocapsule; cellular tumor with fascicles or haphazard pattern; bland spindle cells with scant lightly eosinophilic cytoplasm with ill defined borders, oval to fusiform nucleus; may be epithelioid; occasional atypia; prominent small to medium-sized vessels with hyaline fibrosis in walls; vessels may have degenerative changes of fibrin thrombi, intramural inflammation, hemosiderin; some (usually 5% or less) adipose tissue present in 50%; stroma is usually fine collagenous fibers; scattered mast cells are common; females may have brisk mitotic activity, usually none/rare in males; no necrosis, no atypical mitotic figures
Positive stains: ER, PgR, vimentin; smooth muscle actin (21%), CD34 (30-60%)
Negative stains: S100, actin, desmin, EMA
Cytogenetics: may have 13q14 involvement; similar changes as spindle cell lipoma (Cancer Genet Cytogenet 2007;177:131)
DD: aggressive angiomyxoma, angiomyofibroblastoma (less uniform cellularity, smaller vessels, usually desmin+), solitary fibrous tumor, perineuroma, leiomyoma
References: Stanford School of Medicine
Dermatofibrosarcoma protuberans (DFSP) - Soft Tissue Tumor chapter
Definition: low to intermediate grade malignancy, usually of dermis, with prominent storiform pattern of monomorphic fibroblast-like cells that invade into subcutis
Also called intermediate (borderline) fibrous histiocytoma
Part of WHO classification for skin tumors, not soft tissue tumors
Slow growing, low-grade malignant neoplasm of trunk and various sites but not hands and feet
Rare, usually adults 20-40 years, more common in blacks in US (J Am Acad Dermatol 2007;56:968)
Can occur in infants (Arch Dermatol 2007;143:203) and children (J Plast Reconstr Aesthet Surg 2007 Dec 18 [Epub ahead of print])
May be a peculiar type of nerve sheath tumor since CD34 positive
Locally aggressive, low rate of metastasis (only after repeated failures at local control); may progress to fibrosarcoma or MFH
Giant cell fibroblastoma is considered the juvenile variant of DFSP as it has the same translocation (AJSP 2003;27:27)
Bednar’s tumor: 5-10% of cases; pigmented variant due to dendritic cells with melanin, S100+ only in pigmented cells, HMB45 negative; associated with black patients
Case reports: atrophic variant (J Dermatol 2006;33:486), granular cell variant (AJSP 2002;26:932), myoid differentiation in fibrosarcomatous DFSP (Acta Dermatovenerol Alp Panonica Adriat 2006;15:39), sclerosing variant (Int J Dermatol 2006;45:59)
Treatment: must excise subcutaneous fat (wide local excision with 2-3 cm margins) to prevent recurrence (