Musculoskeletal Pathology Part III Soft Tissue Tumours.
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Transcript of Musculoskeletal Pathology Part III Soft Tissue Tumours.
Musculoskeletal PathologyPart III
Soft Tissue Tumours
Soft tissue tumors
non-skeletal mesodermal tissues: adipose tissue, fibrous tissue, muscle, blood vessels and peripheral nerves (despite neuroectodermal origin)
benign, malignant and intermediate (low-grade malignant – locally aggressive, can recur, no metastatic potential)
originate from primitive mesenchymal stem cells
classification according to differentiation lines (e.g. liposarcoma is not a tumor arising from adipose tissue but exhibiting lipoblastic differentiation)
Classification of soft tissue tumors
Lipomatous tumorsLipomaLiposarcomaSmooth muscle tumorsLeiomyomaLeiomyosarcomaSkeletal muscle tumorsRhabdomyomaRhabdomyosarcomaFibroblastic tumorsNodular fasciitisFibromatosesFibrosarcoma
Fibrohistiocytic tumorsBenign fibrous histiocytomaMalignant fibrous histiocytomaVascular tumorsHemangiomaAngiosarcomaTumors of peripheral nervesSchwannomaNeurofibromaMalignant peripheral nerve sheath
tumorTumors of uncertain originSynovial sarcoma
Lipomathe most common soft tissue tumor in adultsmiddle-aged and elderly peoplesubcutaneous tissue of the trunk and limbs (superficial lipoma)deep soft tissue (deep lipoma)synovial membrane (lipoma arborescens)soft, slowly growing masswell circumscribed, lobular arrangement, yellow cut surfacewell-defined lobules of mature adipose tissuenumerous histologic subtypes (angiolipoma, myolipoma, chondroid lipoma, pleomorphic/spindle cel lipoma)
Liposarcoma
most common malignant soft tissue tumoradults (peak incidence 40-60 years)lower limb and retroperitoneal spacekey diagnostic feature: multivacuolated lipoblast (two or more lipid droplets within the cytoplasm)
well-differentiated lipoma-like liposarcoma (atypical lipomatous tumor): closely resemble lipoma, but a few spindle or stellate cells with hyperchromatic atypical nuclei, high recurrence rate, no meastases (intermediate behaviour)
myxoid liposarcoma: small undifferentiated mesenchymal cells and lipoblast set in a myxoid stroma, plexiform „chicken-wire“ network of capillaries, good prognosis, rare metastases
pleomorphic liposarcoma: mixed cell population (spindle cells, tumor giant cells and small number of lipoblasts), poor prognosis, frequent metastases
Leiomyoma
skin, subcutaneous tissue, uterus, gastrointestinal tract
interlacing bundles of well-differentiated smooth muscle cells with bright
eosinophilic cytoplasm and blunt-ended nuclei
Leiomyosarcoma
mesentery, retroperitoneal space, wall of large veins, skin, subcutaneous tissue, deep soft tissues of limbs
signs of malignancy: large size, high mitotic rate, areas of necrosis, marked cellular pleomorphism
Rhabdomyoma
extremely rare lesions
adult type: head and neck of middle aged individuals, large round or polygonal cells with eosinophilic cytoplasm and abundant cytoplasmatic glycogen
genital type: polypoid growth of the cervix, vagina or vulva in middle age, large rhabdomyoblasts with cross-striations
fetal type: boys younger than 3 years, head and neck, mixture of immature skeletal muscle and loose, rather myxoid stroma
cardiac rhabdomyoma: infancy, fatal by the age of 5 years, association with tuberous sclerosis (50%)usually multiple rounded nodules involving heart ventricleslarge polygonal cells with central mass of eosinophilic cytoplasm, abundant glycogen and narrow processes extending to the periphery (“spider cells“)
Rhabdomyosarcoma
most common malignant soft tissue tumour in infants and young children
rhabdomyoblasts (round, elongated or oval cells with excentric eosinophilic cytoplasm – “tadpole cells, strap cells, racket cells“)
embryonal rhabdomyosarcoma: most common, early childhood, head and neck region (orbit, nasopharynx, middle ear) and genitourinary system, small rounded or spindle-shaped cells within a myxoid matrixbothryoid rhabdomyosarcoma (grape-like): embryonal rhabdomyosarcoma with polypoid configuration and myxoid consistency, occurs in mucosa-lined organs
alveolar rhabdomyosarcoma: 10 - 20 years, muscles of limbs and trunk, honecomb-like spaces bounded by fibrous septa, spaces lined by small round or oval undiffernentiated cells, loss of cohesion towards the centre of spaces
pleomorphic rhabdomyosarcoma: limbs of adults, large cells with eosinophilic cytoplasm and either single or multiple highly atypical nuclei
Nodular fasciitis
benign fibroblastic proliferationadolescents and young adultsrapidly growing nodule within subcutaneous tissue, forearm is the most common site
plump immature fibroblasts arranged in short bundles, numerous mitoses, cellular pleomorphism not present
Superficial fibromatoses
palmar fibromatosis (Dupuytren’s contracture): middle-aged men, nodular thickening of palmar aponeurosis leading later to flexion deformities of fingers
plantar fibromatosis (Ledderhose’s disease): nodular thickening of plantar aponeurosis
penile fibromatosis (Peyronie’s disease): abnormal curvature of penis
nodules of well-differentiated fibroblasts arranged in long sweeping bundles
Deep fibromatoses (desmoid tumors)
abdominal: abdominal wall, young adults, particularly women, often in peripartum or postpartum period, sometimes in surgical scars
intra-abdominal: young adults, mesentery, association with Gardner’s syndrome (intestinal polyposis)
extra-abdominal: the most aggressive, adults in the third and fourth decades, pectoral and pelvic girdles
deep intramuscular location, large size (up to 10-15cm), infiltrative growth pattern, high risk of recurrence after excision
Fibrosarcoma
uncommon malignant neoplasmmiddle aged adultsdeep soft tissues of lower limbs and trunk
bundles of spindle shaped cells arranged at angles to one another (“herring-bone pattern“), frequent mitoses
infantile fibrosarcoma: within the first two years of life, much better prognosis
Benign fibrous histiocytoma (dermatofibroma)
common lesion, most frequently on the skin of lower leg
papule or nodule, often deeply pigmented
situated within the mid-dermis
spindle cells arranged in curious whorled pattern (storiform pattern)
Malignant fibrous histiocytoma (MFH)
deep soft tissues of limbs, retroperitoneum
irregularly arranged plump, eosinophilic, spindle-shaped cells with darkly staining and often bizarre nuclei, numerous mitoses, interspersed macrophage-like cells, storiform pattern in some areas
MFH represents merely a morphological pattern shared by wide variety of poorly differentiated malignant neoplasms, it is a heterogeneous group of unrelated lesions (pleomorphic sarcomas, dedifferentiated carcinomas, high-grade lymhomas etc.)
MFH (synonymous designation: undifferentiated pleomorphic sarcoma) – diagnosis of exclusion following thorough sampling and judicious use of ancillary techniques (immunohistochemistry, electron microscopy)
Haemangioma
hamartomas rather than true neoplasms
capillary haemangioma: skin, mass of proliferated capillaries
pyogenic granuloma: rapidly developing polypoid nodule, many small capillaries similar to those seen in granulation tissue, myxoid stroma, surface often eroded
cavernous haemangioma: skin, liver, aggregates of large dilated thin-walled vessels lined by flattened endothelium
Angiosarcoma
irregular anastomosing vascular spaces lined by endothelial cells with large hyperchromatic nucleihighly aggressive tumor with poor prognosis
Kaposi’s sarcomavariant of angiosarcomaoften patients with AIDSmultiple bluish plaques and nodules on the skin of lower extremitiesspindle-shaped cells with the presence of red cells containing slits and haemosiderin deposition
Schwannoma (neurilemmoma)
smooth lobulated lesion usually attached to a nerve
Antoni A – compact areas formed by regular interlacing bundles of uniform spindle-shaped cells, often foci of nuclear palisading
Antoni B – looser open areas, small cells with rounded nuclei
Neurofibroma
not infrequently multiplesometimes part of neurofibromatosisfusiform expansion of affected nerve
spindle-shaped cells with elongated wavy nuclei set in myxoid stroma
Malignant peripheral nerve sheath tumor (MPNST)
adultsmost common locations: neck, forearm, lower leg, buttocklarge mass producing fusiform enlargement of a major nerverelatively uniform spindle-shaped cells with hyperchromatic nuclei and high mitotic activity
Synovial sarcoma
neither derived from nor differentiates to synovial lining cells (historical name has been retained)young adults (15-40 years)extraarticular soft tissues, often near joint capsules and tendons
two cell types:epithelial (forming nests and gland-like spaces – resembles carcinoma)spindle (arranged in sheets – resembles fibrosarcoma)
biphasic (both cell types)monophasic (spindle or epithelial cells only)
frequent reccurences, metastases in lymph nodes and lungs