Section 9Section 9 Mesenchymal Mesenchymal TumorsTumors

1. Benign (1) Fibroma Grossly: firm, encapsulated masses,

whitish

Histological: interlacing bundles of mature fibrocytes, fibroblasts, and collagen fibers.

Site: commonly in subcutaneous tissue, fascia periosteum ovary

Fibroma

* Formatives: tumor like growths of fibrous tissue in the soft tissue, e. g. dermatofibroma, nodular facilities, juvenile aponeurotic fibroma, desmoid fibromatosis, keloid, and palmar fibromatosis

(2) LipomaGross: lobulated mass with thin

capsule, greasy on cut surface, yellowish in color.

Histological: composed of mature fat cells.

Site: Commonly in the subcutaneous tissue of arms, shoulder, and buttocks

Lipoma

(3) HemangiomaUsually congenital but may be acquired. Gross: Portwine colored, soft, poorly

defined lesion Histological: Composed of blood

vessels, invasive growth partner.Type: ① Capillary type commonly in skin or

mucous membrane② Cavernous type commonly in skin,

spleen, liver.

HemangiomHemangiomaa

(offered by Prof.Orr)

(4) Lymphangioma or cystic hygroma

Usual congenital

Gross: Pale, soft, poorly defined lesion

Histological: Composed of lymphatic vessels.

右颈部囊状水瘤(offered by Prof.Orr)

(5) Leiomyoma Gross: A single or multiple, firm,

circumscribed Histological: Spindle shaped smooth

muscle cells, interwoven fibers of fusiform, varying amounts of connective tissue.

Site: Commonly in uterus, gastrointestinal tract tongue

Leiomyoma

(6) Osteoma Mainly found in skull and the long

bones

(7) Chondroma Gross: firm, bluish with fibrous

capsule, sometimes central softening with brownish fluid.

2. Malignant

(1) Fibrosarcoma

The more the cellularity and the number of mitotic figures, the greater the malignancy

Fibrosarcoma

(2) Rhabdomyosarcoma

Type: ① Embryonal rhabdomyosarcoma: Most common type occurs in children

often arise in the nasal cavity, orbit, middle ear, prostate, and Para testicular region.

Various stages of embryogenesis round and spindled cells in a variably myxoid stroma.

Fetal rhabdomyosarcoma （吴名耀提供）

② Alveolar rhabdomyosarcoma Occur in early to mid adolescence Commonly arise in the deep

musculature of extremities pulmonary alveolae like.

③ Pleomorphic rhabdomyosarcoma Numerous large, multinucleated,

bizarre eosinophilic tumor cells

Pleomorphic rhabdomyosarcomaPleomorphic rhabdomyosarcoma

(3) Osteosarcoma A highly malignant tumor of bone Infiltrative growth manner both

into the marrows and outwards into the surrounding soft tissue. Formatting tumor osteoid by the tumor cells. Some characteristics: “sunburst” appearance, codman’s triangle

Osteosarcoma (Quoted from Robbins 《 Pathology Basis of disease 》 )

(4) Liposarcoma

Commonly occur in the buttocks, lower limbs, retroperitoneum. Composed of embryonic fat cells containing small fat globules in cytoplasm.

大腿脂肪肉瘤 A 手术前外观 B CT 影象 C 手术切除标本 D 镜下 ( 由宋建新主任医师提供 )

(5) 血管肉瘤 (angiosarcoma)

50 岁男性肩胛骨血管肉瘤， 左 1 为 X 线改变， 左 2 、 3 镜下改变 (offered by Prof.Orr) ，左 4 免疫组化上皮标记 CD31 呈阳性（ quoted from Robbins Basic Pathology)

(6) Kaposi 肉瘤 可能来源于血管内皮或原始间叶细胞的梭形细胞肉瘤。

Quoted form Robbins Basic Pathology, 2003

(6) Kaposi 肉瘤

Quoted from Robbins Basic Pathology, 2003

(7) Malignant fibrous histiocytoma

Refer to a heterogeneous group of aggressive soft tissue tumors characterized by considerable cytologist plemorphism. Spindled cells in swirling (storiform) pattern.

(8) Malignant lymphoma

(9) Leukemia

3. Comparisons Between Carcinoma and

Sarcoma

Carcinoma Sarcoma① Histogenesis Epithelial tissues Mesenchymal

tissues

② Morbidity High. In older age Low. In children & young

③ Gross Hard, gray-white, dry

Soft, fleshy

④ Histologicaly Form carcinoma nests, so, there are clear line of demark- ation between nests & sup-ortive stroma.

Tumor cells diffuse in supportive stroma, so, there are not marked boundary between parenchyma & supportive stroma.

Carcinoma Sarcoma

⑤ Reticular fiberStaining:

Around carcinoma nest,no around tumor cells.

Around tumor cells

⑥ Metastasis: Most frequently via lymphatics.

Most frequently via blood vessels.

1. The central nervous tumors

(1) Glioma ① Astrocytoma ② Oligodendroglioma ③ Ependymoma

(2) Medulloblastoma

(3) Meningioma

2. Peripheral nervous tumors

(1) Neurofibroma

(2) Neurilemmoma

NeurilemmoNeurilemmomama

(offered by Prof.Orr)

3. Retinoblastoma

4. Pigmented nevus and melanoma

(1) Pigmented nevus Most authorities agree that the

melanocytes are derived from neuro-ectoderm, and migrate to the basal layer of the skin in early intrauterine life

A nevus or more implies a benign pigmented tumor containing nevus cells.

(2) Melanoma Malignant Gross: a variably pigmented, rapidly

rowing, Ulcerated and bleeding lesion of the skin

Histological: Pleomorphic, melanin- containing cellsinvading the underlying tissues.

Amelanotic melanoma: Someone have no melaning pigment, but still DOPA positive.

melanoma