آزمايشگاه رز - Ackerman Atlas(chaptr41)

Soft Tissue

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Figure 41.1 Gross appearance of calcifying aponeurotic fibroma. The mass is unencapsulated and ill defined

Figure 41.2 Low-power appearance of calcifying aponeurotic fibroma

Figure 41.3 Calcifying Aponeurotic Fibroma. A, Tumor cells emanate from calcifications. B, High-power view of calcifying aponeurotic fibroma with bland spindle to round cells associated with calcifications and a single giant cell

Figure 41.4 Fibroma of Tendon Sheath. The lesion is hypocellular and contains abundant collagen

Figure 41.5 Collagenous Fibroma. A, The lesion is well circumscribed and hypocellular. B, The cells are spindle to stellate shaped

Figure 41.6 Superficial Acral Fibromyxoma. A, The dermis is expanded by a nodular proliferation of bland spindle cells deposited in a fibromyxoid matrix. B, Bland spindle cells are arranged in a vaguely whorled growth pattern. C, Strong CD34 staining in the neoplastic cells

Figure 41.7 Fibrous Hamartoma of Infancy. A, An admixture of cellular fibrous foci and mature adipose tissue. B, A cellular spindle cell focus is seen surrounding mature adipose tissue. C, High-power view showing an oval cluster of plump mesenchymal cells

Figure 41.8 Panoramic View of Nodular Fasciitis. The lesion is small, ill defined, and centered in the subcutaneous tissue

Figure 41.9 Strikingly cellular zone in nodular fasciitis

Figure 41.10 Nodular fasciitis with prominent collagen deposition and scattered giant cells

Figure 41.11 Nodular Fasciitis. A, Area of myxoid degeneration in nodular fasciitis. B, The proliferation involves the wall and lumen of blood vessels. C, High-power view of reactive myofibroblasts in nodular fasciitis

Figure 41.12 Ganglion-like cells in proliferative fasciitis

Figure 41.13 Gross Appearance of Proliferative Myositis. There is ill-defined whitish material in between the skeletal muscle fibers

Figure 41.14 Low-power checkerboard appearance of proliferative myositis

Figure 41.15 On high-power, the ganglion-like cells of proliferative myositis look similar to those of proliferative fasciitis (see Fig. 41.12)

Figure 41.16 Ischemic Fasciitis. A, Central area of fibrinous necrosis surrounded by a proliferation of blood vessels and myofibroblasts. B, Junction of area of fibrinous necrosis and proliferating blood vessels resembling granulation tissue. C, High-power view of atypical stromal cells in an area of vascular proliferation

Figure 41.17 Myositis Ossificans. A, Interface between reactive bone and reactive myofibroblasts in myositis ossificans. B, High-power view of reactive myofibroblasts

Figure 41.18 Intranodal Palisaded Myofibroblastoma. A, Bland spindle cells and brightly eosinophilic collagen. B, High-power view with char- acteristic amianthoid-like collagen

Figure 41.19 Mammary-Type Myofibroblastoma. A, Low-power view. B, The lesion is composed of bland spindle cells and dense collagen

Figure 41.20 Gross appearance of elastofibroma

Figure 41.21 Low-power view of elastofibroma with an irregularly shaped fibrohyaline mass within adipose tissue

Figure 41.22 High-power view of elastofibroma showing (A) diagnostic rods of elastic tissue (B, elastic tissue stain)

Figure 41.23 Solitary fibrous tumor showing a prominent hemangio- pericytoma-like vascular pattern and variable cellularity

Figure 41.24 Solitary Fibrous Tumor. A, Prominent hemangiopericytoma- like vascular pattern. B, Hypocellular zone. C, Wire-like collagen in solitary fibrous tumor

Figure 41.25 Deep-seated fibromatosis embedded within major skeletal muscle

Figure 41.26 Low-power view of abdominal wall fibromatosis with a cellular proliferation arranged in fascicles associated with prominent blood vessels

Figure 41.27 Abdominal Wall Fibromatosis. A, High-power view of cells in fibromatosis. B, Keloid-like collagen is often seen

Figure 41.28 Inclusion Body Fibromatosis. A, Spindle cells with eosinophilic inclusions are seen. B, Trichrome stain revealing rare eosinophilic inclusions

Figure 41.29 Infantile Myofibroma. A, Low-power view with central cellular zone with a hemangiopericytoma-like pattern and a peripheral myoid zone. B, Junction of hemangiopericytoma-like zone and myoid zone. C, High-power view of myoid zone in infantile myofibroma

Figure 41.30 Plantar Fibromatosis. The tissue is whitish and unencapsulated with an elastic consistency

Figure 41.31 Well-circumscribed fibrosarcoma growing within skeletal muscle

Figure 41.32 Adult-Type Fibrosarcoma. A, Low-power view. B, High- power view

Figure 41.33 Characteristic low-power appearance of low-grade fibromyxoid sarcoma with alternating fibrous and myxoid zones

Figure 41.34 Low-grade fibromyxoid sarcoma with prominent blood vessels and perivascular hypercellularity

Figure 41.35 Bland spindle cells within myxoid stroma in low-grade fibromyxoid sarcoma

Figure 41.36 Collagen rosettes in a low-grade fibromyxoid sarcoma

Figure 41.37 Sclerosing epithelioid fibrosarcoma. The single file disposition of cells simulates carcinoma

Figure 41.38 Myxoinflammatory Fibroblastic Sarcoma. A, Low-power view showing a heterogeneous appearance with alternating cellular and myxoid zones. B, Pseudolipoblasts and enlarged atypical smudgy cells can be seen

Figure 41.39 Inflammatory Myofibroblastic Tumor. A, Cellular zone with spindle cells and scattered inflammatory cells. B, High-power view of myofibroblasts. C, "Tram track" pattern of smooth muscle actin staining of myofibroblasts

Figure 41.40 Cellular zone of a myofibrosarcoma with plump spindle cells arranged in fascicles

Figure 41.41 Low-power view of classical benign fibrous histiocytoma. The lesion is well circumscribed at its base, and epidermal hyperplasia is apparent

Figure 41.42 Storiform zone in classical benign fibrous histiocytoma

Figure 41.43 Classical Benign Fibrous Histiocytoma. A, Scattered multinucleated giant cells and foam cells are seen. B, Collagen trapping is often seen at the lateral edge

Figure 41.44 Cellular benign fibrous histiocytoma composed of a highly cellular proliferation arranged into fascicles. This is easily mistaken for a sarcoma

Figure 41.45 Scattered bizarre cells in atypical benign fibrous histiocytoma

Figure 41.46 Low-power view of aneurysmal benign fibrous histiocytoma with tumor-lined blood-filled lakes

Figure 41.47 Cellular Neurothekeoma. A, Nests of plump spindle cells separated by collagen bands. B, High-power view of cellular neurothekeoma

Figure 41.48 Dermatofibrosarcoma Protuberans. A, Characteristic storiform pattern. B, Lace-like infiltration into fat at the base of a derma- tofibrosarcoma protuberans

Figure 41.49 Giant cell fibroblastoma with myxoid and pseudovascular spaces lined by atypical giant cells

Figure 41.50 Pigmented dermatofibrosarcoma protuberans (Bednar tumor). Scattered pigmented cells are seen among the spindle cells

Figure 41.51 Fibrosarcomatous transformation of a dermatofibrosarcoma protuberans with a herringbone spindle cell pattern

Figure 41.52 Angiomatoid Fibrous Histiocytoma. A, Low-power view closely mimicking a tumor metastasis to a lymph node. B, Blood lake in angiomatoid fibrous histiocytoma

Figure 41.53 Hemosiderin deposition in histiocyte-like tumor cells in angiomatoid fibrous histiocytoma

Figure 41.54 Eosinophilic histiocyte-like cells in a solid zone of angio- matoid fibrous histiocytoma

Figure 41.55 Plexiform Fibrohistiocytic Tumor. A, Nodules of spindle cells in a myxoid stroma are arranged in a plexiform pattern. B, Nodules of histiocytoid cells with rare giant cells are often seen

Figure 41.56 Giant Cell Tumor of Soft Tissue. A, Nodules of giant cells are seen. B, High-power view of giant cells within a nodule

Figure 41.57 Large undifferentiated pleomorphic sarcoma with areas of necrosis

Figure 41.58 Undifferentiated Pleomorphic Sarcoma. A, Prominent storiform growth pattern. B, Marked nuclear pleomorphism and scattered giant cells are seen

Figure 41.59 Undifferentiated pleomorphic sarcoma with very focal myxoid change comprising less than 5% of the tumor

Figure 41.60 Undifferentiated pleomorphic sarcoma with prominent acute inflammation, a lesion formerly known as "inflammatory MFH

Figure 41.61 Myxofibrosarcoma, Formerly Known as "Myxoid MFH." A, Alternation of cellular and myxoid zones. B, There is moderate nuclear pleomorphism of the tumor cells. C, Rare lipoblast-like cells (pseudolipoblasts) are often seen

Figure 41.62 Myxofibrosarcoma with arborizing blood vessels and perivascular hypercellularity

Figure 41.63 Giant cell tumor of tendon sheath with linear arrays of mononuclear cells deposited in a collagen background admixed with multinucleated giant cells

Figure 41.64 A monotonous population of mononuclear cells in a giant cell tumor of tendon sheath. No giant cells are seen in this case

Figure 41.65 Sheets of mononuclear cells and xanthoma cells in a diffuse- type giant cell tumor

Figure 41.66 Traumatic neuroma with a haphazard distribution of nerve trunks surrounded by fibrous tissue

Figure 41.67 Schematic drawing emphasizing the main differences between the three major types of peripheral nerve tumors. Note diameter of nerve involved and behavior of neurites (thin black lines) in relation to the neoplasm. MPNST, malignant peripheral nerve sheath tumor

Figure 41.68 Gross Appearances of Schwannoma. The tumor shown in B has undergone marked secondary cystic changes

Figure 41.69 Low-power view of schwannoma with capsule and Antoni A and B areas

Figure 41.70 Junction of Antoni A and B zones in a schwannoma

Figure 41.71 Verocay bodies in a schwannoma

Figure 41.72 Schwannoma. A, Large hyperchromatic nuclei are seen. This does not necessarily indicate malignant change. B, Thick-walled hyalinized blood vessels are a prominent feature

Figure 41.73 Epithelioid schwannoma with epithelioid Schwann cells deposited in a myxoid matrix

Figure 41.74 S-100 protein immunoreactivity in a schwannoma

Figure 41.75 Cellular schwannoma with a compact proliferation of spindle cells arranged in short fascicles. Verocay bodies are not seen

Figure 41.76 Psammomatous melanotic schwannoma in a patient with Carney syndrome

Figure 41.77 Granular Cell Tumor of Skin. There is an ill-defined permeation of the dermis by whitish tissue

Figure 41.78 Granular Cell Tumor. The cells contain innumerable fine cytoplasmic granules as well as scattered larger eosinophilic globules

Figure 41.79 Pseudoepitheliomatous hyperplasia in squamous epithelium overlying a granular cell tumor

Figure 41.80 Granular cell tumor growing concentrically within and around a nerve cut transversely

Figure 41.81 Well-circumscribed neurofibroma of soft tissue. The tumor has a gelatinous appearance

Figure 41.82 Typical gross appearance of a plexiform neurofibroma. This tumor is indicative of neurofibromatosis type 1

Figure 41.83 Neurofibroma with spindle cells deposited in a collagen matrix with a "shredded carrot" appearance

Figure 41.84 Neurofibroma with large bizarre hyperchromatic nuclei

Figure 41.85 Marked deformation of distal upper extremity by diffuse neurofibromatosis. This patient developed a malignant peripheral nerve sheath tumor

Figure 41.86 A and B, Two morphologic appearances of perineurioma. The tumor shown in A simulates a myxofibrosarcoma

Figure 41.87 Electron Microscopic Appearance of Perineurioma. Thin perineurial cell cytoplasmic processes with prominent pinocytotic vesicles. The processes are coated by a continuous basal lamina. (×42000; Courtesy of Dr. Robert A. Erlandson, Memorial Sloan-Kettering Cancer Center.)

Figure 41.88 Epithelial membrane antigen immunoreactivity in perineurioma

Figure 41.89 Dermal Nerve Sheath Myxoma. A, Low power. B, Medium power. C, High power. The lesion has a distinct lobulated appearance

Figure 41.90 Malignant Peripheral Nerve Sheath Tumor. The marked hypercellularity and high mitotic activity in the absence of significant pleomorphism are commonly seen in this tumor type

Figure 41.91 Malignant peripheral nerve sheath tumor with plump, almost epithelioid cells surrounding a blood vessel, a common feature of this tumor

Figure 41.92 Malignant peripheral nerve sheath tumor with an area of necrosis

Figure 41.93 Malignant peripheral nerve sheath tumor with divergent angiosarcomatous differentiation as well as rare mucin-producing glands

Figure 41.94 Malignant peripheral nerve sheath tumor with rhabdomyosarcomatous differentiation (so-called Triton tumor, A) with positive immunoreactivity for myoglobin (B)

Figure 41.95 Epithelioid malignant peripheral nerve sheath tumor

Figure 41.96 Strong S-100 protein immunoreactivity in epithelioid malignant peripheral nerve sheath tumor

Figure 41.97 Patchy S-100 protein immunoreactivity in a spindle cell type of malignant peripheral nerve sheath tumor

Figure 41.98 Gross Appearance of Lipoma. Except for the circumscrip- tion, the appearance is indistinguishable from that of normal fat

Figure 41.99 Chondroid Lipoma. A, Low-power and B, High-power views

Figure 41.100 Spindle Cell Lipoma. Ropey collagen is a prominent feature

Figure 41.101 A and B, Spindle cell lipoma with a pseudoangiomatous appearance resulting from accumulation of tumor cells beneath artifactual tissue spaces

Figure 41.102 A and B, Pleomorphic lipoma with characteristic floret-type giant cells

Figure 41.103 Strong CD34 staining in a pleomorphic lipoma

Figure 41.104 Angiolipoma. A, Intimate admixture of blood vessels and mature adipose tissue. B, Numerous fibrin thrombi can be seen

Figure 41.105 Intramuscular lipoma with interdigitation of mature adipose tissue and skeletal muscle

Figure 41.106 Lipoblastoma. A, Lobulated appearance and nodules of both mature adipose tissue and others with myxoid change. B, A myxoid nodule in a lipoblastoma showing some resemblance to myxoid liposarcoma. C, Area of mature adipose tissue in lipoblastoma

Figure 41.107 A, Gross appearance of benign adipose tissue that had features of both hibernoma and lipoma. Low-power (B) and high-power (C) views of a hibernoma

Figure 41.108 A, Gross and B, Microscopic appearance of fibrolipo- matous hamartoma of nerve

Figure 41.109 Atypical Lipomatous Tumor. The neoplasm is well circumscribed and not much different from an ordinary lipoma

Figure 41.110 Gross appearance of a retroperitoneal atypical lipomatous tumor (well-differentiated liposarcoma) that microscopically combined features of the sclerosing and lipoma-like subtypes

Figure 41.111 Low-power view of atypical lipomatous tumor with fibrous bands and enlarged hyperchromatic nuclei identified within the fibrous bands

Figure 41.112 High-power view of atypical nucleus in atypical lipomatous tumor

Figure 41.113 Typical lipoblasts from a case of metastatic liposarcoma showing nuclear indentation by lipid-containing cytoplasmic vacuoles

Figure 41.114 Hyperchromatic atypical nucleus in lipoma-like atypical lipomatous tumor

Figure 41.115 Myxoid area of atypical lipomatous tumor with rare atypical cells

Figure 41.116 Inflammatory-type atypical lipomatous tumor with atypica nucleus amongst a dense lymphoplasmacytic infiltrate

Figure 41.117 Fluorescence in situ hybridization showing amplification of MDM2 (green signal) in atypical lipomatous tumor

Figure 41.118 A and B, Myxoid liposarcoma

Figure 41.119 Round Cell Liposarcoma. This tumor is a poorly dif- ferentiated form of myxoid liposarcoma

Figure 41.120 Epithelioid variant of pleomorphic liposarcoma (A). The liposarcomatous nature of the tumor is better shown in B

Figure 41.121 Dedifferentiated liposarcoma of retroperitoneum abutting the kidney, a common occurrence

Figure 41.122 Dedifferentiated retroperitoneal liposarcoma. A, Divergent rhabdomyosarcomatous differentiation with (B) desmin immunoreactivity

Figure 41.123 Area of so-called low-grade dedifferentiation which is devoid of adipocytic differentiation. This area shows extensive myxoid change and is more cellular than the usual atypical lipomatous tumor

Figure 41.124 Massive lymphedema in a morbidly obese patient resembling an atypical lipomatous tumor

Figure 41.125 Infantile hemangioma. A, Vaguely lobulated architecture. B, The high cellularity and mitotic activity should not lead to an overdi- agnosis of malignancy

Figure 41.126 Cavernous hemangioma of soft tissues of the orbit

Figure 41.127 Cavernous hemangioma with widely dilated vascular spaces

Figure 41.128 Gross appearance of an intramuscular hemangioma

Figure 41.129 Intravascular Papillary Endothelial Hyperplasia. The confinement of the lesion to the vascular lumen with hyaline cores within the papillae is a characteristic feature

Figure 41.130 Low-power view of spindle cell hemangioma with rare phleboliths

Figure 41.131 Spindle Cell Hemangioma. A, Cavemous spaces admixed with Kaposi-like spindle cells. B, Kaposi-like areas are prominent in this case

Figure 41.132 Epithelioid Hemangioendothelioma. A, Prominent cytoplasmic vacuolization resembling lipoblasts. B, Strong nuclear immunoreactivity for ERG is seen

Figure 41.133 Intraluminal papillations with fibrous cores lined by hobnail endothelial cells in hobnail hemangioendothelioma, Dabska-type

Figure 41.134 Gross hemorrhagic appearance of angiosarcoma in the region of the hip

Figure 41.135 Angiosarcoma of the mediastinum showing anastomosing vascular channels

Figure 41.136 Epithelioid angiosarcoma with large epithelioid cells arranged in sheets and vasoformative spaces

Figure 41.137 Cavernous Lymphangioma. (Courtesy of Dr. R.A. Cooke, Brisbane, Australia; from Cooke RA, Stewart B. Colour Atlas of Anatomical Pathology. Edinburgh: Churchill Livingstone; 2004.)

Figure 41.138 Lymphangioma of soft tissue showing dilated spaces lined by flattened endothelium. A scattering of lymphocytes is present in the stroma

Figure 41.139 Amputated upper extremity in a case of post-mastectomy angiosarcoma

Figure 41.140 Post-mastectomy angiosarcoma showing an intricate network of neoplastic vessels

Figure 41.141 Vascular leiomyoma (angioleiomyoma) with neoplastic smooth muscle cells closely related to blood vessels

Figure 41.142 Vascular leiomyoma (angioleiomyoma) with scattered bizarre tumor cells, a feature of no prognostic significance

Figure 41.143 Leiomyosarcoma of Soft Tissues of the Arm. The fusiform shape of the tumor is due to the tumor following the course of the large blood vessels from which it arose

Figure 41.144 Leiomyosarcoma filling the lumen of the popliteal vein and its branches, as seen on cross section. The popliteal artery is uninvolved

Figure 41.145 A, Low-power and B, High-power views of a leiomyo- sarcoma with arrangement into fascicles

Figure 41.146 Immunoreactivity for low-molecular-weight cytokeratin (CAM5.2) in leiomyosarcoma

Figure 41.147 Epithelioid leiomyosarcoma composed of malignant epithelioid cells and rare giant cells

Figure 41.148 A, Glomus tumor with round glomus cells surrounding open vascular spaces. B, Strong SMA immunoreactivity is characteristic

Figure 41.149 Myxoid zone in a glomus tumor

Figure 41.150 Glomangiopericytoma. A, Low-power and B, High-power views

Figure 41.151 Fetal rhabdomyoma with eosinophilic spindle cells and rare cells with obvious cross striations

Figure 41.152 Pleomorphic rhabdomyosarcoma showing some resem- blance to an undifferentiated pleomorphic sarcoma but with rare eosino- philic giant cells. This tumor stained for both desmin and myogenin

Figure 41.153 Embryonal Rhabdomyosarcoma. Most of the nuclei are oval; the cytoplasm is scanty and acidophilic

Figure 41.154 Botryoid rhabdomyosarcoma of common bile duct showing a concentration of tumor cells immediately beneath the epithelium ("cambium layer")

Figure 41.155 Embryonal rhabdomyosarcoma with anaplastic features in a child

Figure 41.156 Gross Appearance of Alveolar Rhabdomyosarcoma. The tumor is embedded within skeletal muscle

Figure 41.157 Typical low-power appearance of alveolar rhabdomyo- sarcoma with alignment of tumor cells along fibrovascular septa

Figure 41.158 Alveolar rhabdomyosarcoma showing a multinucleated tumor giant cell among the smaller mononuclear cells, an important diagnostic clue

Figure 41.159 Strong nuclear immunoreactivity for myogenin (MGEN) in alveolar rhabdomyosarcoma

Figure 41.160 Gross appearance of chondroma of soft tissues of hand. The tumor was partially calcified

Figure 41.161 A, The tumor cells of this soft tissue chondroma have a histiocyte-like quality, similar to that seen in chondroblastoma of bone. B, Soft tissue chondroma with a hypercellular component having osteoclast-like giant cells with some resemblance to chondromyxoid fibroma of bone

Figure 41.162 Lobulated outer appearance of myxoid chondrosarcoma

Figure 41.163 Low-power (A) and high-power (B) views of myxoid chondrosarcoma. There are thin anastomosing strands of tumor cells surrounded by an abundant myxoid matrix. In contrast to myxoid lipo- sarcoma, vascularity is scanty

Figure 41.164 Mesenchymal Chondrosarcoma. Hypercellular areas with hemangiopericytoma-like features are admixed with islands of well- differentiated cartilage

Figure 41.165 Extraskeletal Osteosarcoma. A, The neoplasm is embedded within skeletal muscle and is relatively well circumscribed. B, Extraskeletal osteosarcoma with a central nidus of neoplastic bone

Figure 41.166 Melanotic Neuroectodermal Tumor of Infancy. Nests of neuroblast-like cells are adjacent to gland-like spaces lined by larger cells containing neural-type melanin

Figure 41.167 Myxopapillary ependymoma of the sacrococcygeal region resulting in a huge protruding mass that is focally ulcerated. (Courtesy of Dr. Juan Jose Segura, San Jose, Costa Rica.)

Figure 41.168 Myxopapillary ependymoma involving soft tissues of buttock. The tumor papillae have an abundant hyalinized core

Figure 41.169 Soft Tissue Glioma Involving the Orbit. A, Gross appearance; B, Low-power view; C, High-power view showing the glial fibrillary background and scattered multinucleated cells. This lesion is probably a malformation rather than a true neoplasm

Figure 41.170 Gross appearance of deep-seated synovial sarcoma involving periosteum of the femur in an adolescent boy

Figure 41.171 A, Typical biphasic appearance of synovial sarcoma. B, Synovial sarcoma with an adenocarcinoma-like appearance of the epithelial component

Figure 41.172 A, Radiographic appearance of a calcifying synovial sarcoma located in the popliteal space. B, Microscopic appearance. (A, from Varela-Duran J, Enzinger FM. Calcifying synovial sarcoma. A clinicopathologic study of 32 cases. Cancer. 1982;50:345-352.)

Figure 41.173 A, Low-power view of monophasic synovial sarcoma with spindle cells arranged in fascicles imparting a "marbled" appearance. B, Fascicles of spindle cells in monophasic synovial sarcoma. C, High- power view of uniform, slightly plump spindle cells in monophasic synovial sarcoma

Figure 41.174 Myxoid areas with prominent collagen deposition in monophasic synovial sarcoma

Figure 41.175 Low-power (A) and high-power (B) views of a poorly differentiated synovial sarcoma composed of high-grade round cells surrounding a hemangiopericytoma-like vascular pattern

Figure 41.176 A, Strong nuclear TLE3 immunoreactivity in monophasic synovial sarcoma. B, Strong CD99 immunoreactivity in monophasic synovial sarcoma

Figure 41.177 Typical gross appearance of intramuscular myxoma. (Courtesy of Dr. R.A. Cooke, Brisbane, Australia: from Cooke RA, Stewart B. Colour Atlas of Anatomical Pathology. Edinburgh: Churchill Livingstone; 2004.)

Figure 41.178 Low-power (A) and high-power (B) views of intramuscular myxoma with a paucity of blood vessels

Figure 41.179 Alveolar Soft Part Sarcoma. The tumor is multinodular, relatively well circumscribed, and embedded within skeletal muscle

Figure 41.180 Low-power (A) and high-power (B) views of alveolar soft part sarcoma with a prominent nested growth pattern

Figure 41.181 A, PAS-positive cytoplasmic granules in alveolar soft part sarcoma, some having a crystalline appearance. B, Electron microscopic appearance of alveolar soft part sarcoma. Detailed view of characteristic crystalloid inclusions that demonstrate orderly 70- angstrom periodicity. Both linear and cross-hatched crystalloid pattern may be noted. (x70,000; Courtesy of Dr. J. Sciubba, New Hyde Park, New York.)

Figure 41.182 Metastatic malignant melanoma closely simulating the appearance of alveolar soft part sarcoma

Figure 41.183 Gross appearance of clear cell sarcoma located in the posterior thigh

Figure 41.184 Clear cell sarcoma with nests of cells with clear cytoplasm

Figure 41.185 Low-power (A) and high-power (B) views of epithelioid sarcoma. Central necrobiotic areas simulate granuloma annulare or rheumatoid nodule

Figure 41.186 Remarkable epithelioid quality of tumor cells in epithelioid sarcoma with densely eosinophilic cytoplasm

Figure 41.187 Strong cytokeratin immunoreactivity (CAM5.2) in epithelioid sarcoma

Figure 41.188 Loss of INI1 staining in epithelioid sarcoma. Internal control staining is present in endothelial cells and inflammatory cells

Figure 41.189 Proximal variant of epithelioid sarcoma. Some of the tumor cells have rhabdoid features

Figure 41.190 A, Low-power view of ossifying fibromyxoid tumor with a rim of lamellar bone at the periphery of a tumor nodule. B, High-power view with medium-sized cells arranged in cords embedded in a hyaline matrix

Figure 41.191 Uniform appearance of round cells in classical Ewing sarcoma

Figure 41.192 Low-power appearance of nests of cells in a peripheral primitive neuroectodermal tumor

Figure 41.193 Strong CD99 membranous immunoreactivity in a classical Ewing sarcoma

Figure 41.194 A, Nests of cells deposited on a desmoplastic stroma in desmoplastic small cell tumor. B, High-power view of round cells arranged in nests in desmoplastic small cell tumor

Figure 41.195 A, Strong cytokeratin immunoreactivity in desmoplastic small cell tumor. B, Characteristic perinuclear dot-like pattern of desmin staining

Figure 41.196 Soft tissue tumor of the vulvar region with rhabdoid features

Figure 41.197 Rhabdoid tumor stained for cytokeratin. Perinuclear globular immunoreactivity can be seen in some of the cells

Figure 41.198 Electron microscopic appearance of rhabdoid tumor of soft tissue. The cytoplasmic organelles are displaced by a large aggregate of intermediate filaments. (x15,000; Courtesy of Dr. Robert A. Erlandson, Memorial Sloan-Kettering Cancer Center.)

Figure 41.199 Phosphaturic Mesenchymal Tumor. A, This area has a prominent hemangiopericytoma-like quality. B, This area from the same tumor shows chondroid differentiation and scattered osteoclast-like giant cells

Figure 41.200 A, Pleomorphic hyalinizing angiectatic tumor with pleomorphic tumor cells surrounding dilated blood vessels. B, Intranuclear inclusions are identified in some of the neoplastic cells

Figure 41.201 A, Myoepithelioma of soft tissue closely resembling extraskeletal myxoid chondrosarcoma with cords of cells deposited in a myxoid stroma. B, Parachordoma-like myoepithelioma of soft tissue

Figure 41.202 A, Strong cytokeratin immunoreactivity (CAM5.2) and (B) strong smooth muscle actin staining in myoepithelioma of soft tissue

Figure 41.203 Carcinoma of the large bowel metastatic to soft tissues and skin

Figure 41.204 A, Radiograph showing an area of tumoral calcinosis adjacent to a posterior rib in a 9-year-old child. B, Radiograph of the excised specimen. Calcification is lobulated, splotchy, and independent of the eighth rib

Figure 41.205 Tumoral Calcinosis. A, Gross appearance. The lesion is characteristically multinodular, and the material has a chalky quality. B, Microscopic appearance. Note the absence of cartilaginous features

Figure 41.206 Calcifying fibrous pseudotumor with round calcific concre- tions seen against a fibrohyaline background containing scattered lymphocytes

Figure 41.207 So-called mucicarminophilic histiocytosis. The highly myxoid quality of this lesion may induce confusion with a myxoid neoplasm

Figure 41.208 Gross appearance of Rosai-Dorfman disease (sinus histiocytosis with massive lymphade- nopathy) involving skin and soft tissue in the buttock region

Figure 41.209 A, Characteristic heterogeneous low-power view of Rosai-Dorfman disease of soft tissue. B, Emperipolesis is present in this case. C, Strong S-100 protein immunoreactivity is characteristic