Mesenchymal Tumours and Lymphoma Flashcards Preview

Pathology-IMED4111 > Mesenchymal Tumours and Lymphoma > Flashcards

Flashcards in Mesenchymal Tumours and Lymphoma Deck (28)
Loading flashcards...

What are mesenchymal tumors?

Practically, they can be thought of as non-epithelial, non-melanocytic, non-lymphomatous skin tumors.


What are some of the types of mesenchymal tumors of the skin?

- tumors of fat
- tumors of fibrous tissue
- tumors of blood vessels and lymphatics
- tumors of muscle
- tumors with nerve sheath differentiation


What are malignant mesenchymal tumors called?



Describe benign tumors of fat.

Name: lipomas

Clinically Features:
- age 40+
- associated with obesity
- may be very large
- bright yellow homogenous fat with fine fibrous capsule and trabeculae
- greasy cut surface

Histological features:
- composed of mature adipocytes with uniform nuclei resembling normal white fat
- small amounts of fibrous tissue


What are the variants of lipoma?

These are benign tumors with similar macroscopic appearance but variable microscopic appearance.

- spindle cell lipoma
- chondroid lipoma
- pleomorphic lipoma
- angiolipoma - capillaries more prominent


Describe a malignant fat tumor.

Name: liposarcoma

3 main types:
a) atypical lipotamous tumour/well differentiated liposarcoma
b) myxoid/round cell liposarcoma
c) pleomorphic liposarcoma

Deep soft tissue


What is a dedifferentiated liposarcoma?

A biphasic tumor that includes an undifferentiated sarcomatous component.


What would MDM2 genetic amplification indicate?

Well-differentiated tumors.


What are some of the tumors of fibrous tissue?

a) Dermatofibroma
b) Defmatofibrosarcoma protuberans (DFSP)
c) Atypical Fibroxanthoma (AFX)


Describe Dermatofibroma.

- benign
- common site: legs of women 20-50
- recurrence not common

- tumor is composed of fibroblastic and histiocytic cells arranged in sheets or intersecting fascicles
- mixed population of cells – inflammatory cells consisting of lymphocytes, plasma cells and foamy histiocytes are also seen
- the stroma contains delicate collagen fibers in between cells
- mitotic activity not increased
- cytologic atypia absent
- no sharply defined borders
- usually show entrapment of surrounding dermal collagen
- overlying epithelial hyperplasia and hyperpigmentation


Describe DFSP.

- well differentiated primary fibrosarcoma of the skin
- slow growing, can be locally aggressive and recur, but rarely metastasize
- firm, solid nodules mostly found on trunk

- composed of fibroblasts arranged radially in a stroriform patter (irregular pattern denoting a straw mat)
- mitoses present
- often show deep extendion into subcutaneous fat
- lace-like pattern


What are the key differences between Dermatofibroma and DFSP?

- the deep margin of DF usually shows limited infiltration into subcut tissues, whereas DFSP has more extensive infiltration.
- DSFP has more homogenous population of tumor cells, lacks inflammatory cells, foamy histiocytes and giant cells
- Stratiform pattern more pronounced in DFSP
- Mitotic activity increased in DFSP
- DF = factor 13a positive
- DFSP = CD34 positive


Describe AFX.

- generally rapidly growing nodular lesions in sun exposed areas of older patients
- rapid growth
- usually polypoid without ulceration.
- 1-6cm
- local excisions usually curative and recurrence is rare

- composed of atypical, pleomorphic spindle cells
- storiform or fascicle pattern
- abundant mitoses, but some mitotic figures atypical
- use immunohistochemistry to exclude melanoma, spindled squamous cell carcinoma or leiomyosarcoma. AFX will be negative for S-100, melan A, desmin and cytokeratins.
- overlying epidermis uninvolved


What are some of the tumors of histiocytes?

a) Juvenile Xanthogranuloma (JXG)
b) Fibroepithelial polyp/skin tag/acrochordon


Describe JXG.

- cutaneous histiocytic lesion usually seen in infancy and childhood
- most patients develop lesions by 6 months
- excellent prognosis – most regress spontaneously
- yellow or brown

- composed of sheets of histiocytes (eosinophilic cytoplasm) in dermis and extending to the flattened epidermis
- hallmark = touton giant cell
- inflammatory cells found in moderate numbers


Describe Fibroepithelial polyp/skin tag/acrochordon.

- benign
- middle aged and older people – trunk, face and interigous areas
- soft flesh coloured tumor attached to skin by a slender stalk

- fibrovascular cored covered in squamous epithelium


Name and describe a benign tumor of smooth muscle.

Leiomyoma = benign

Subtypes based on location:
- nipple or scrotum
- pilar leiomyoma
- angioleiomyoma

- intersecting fascicles
- cigar shaped nuclei
- no atypia
- no mitotic activity
- no necrosis


Name and describe a malignant tumor of smooth muscle.

Leiomyosarcoma = malignant

a) Dermal:
- arise from pilar muscles or genital smooth muscles
- middle aged males
- metastasis rare

b) Subcutaneous:
- arise from vascular smooth muscle
- greater tendency for metastasis

Compared to leiomyoma:
- more cellular
- cytological atypia
- mitoses
- necrosis


Name and describe a benign tumor of blood vessels.

a) capillary Haemangiomas – thin walled capillaries
b) juvenile Haemangiomas
c) cavernous Haemangiomas – large, dilated vascular channels
d) lobular capillary Haemangiomas (‘pyogenic granuloma’)
– polypoid, often ulcerate and bleed
- will look like lobulated polyp, capillary sized vessels


Name 2 malignant tumors of blood vessels.

1. Angiosarcoma
2. Kaposi Sarcoma


Describe Angiosarcoma.

- head and neck in eldery
- associated with chronic lymphedema
- post radiation therapy
- slow growing but highly aggressive
- metastasize to regional lymph nodes and organ


Describe Kaposi Sarcoma.

- vascular neoplasm caused by HHV8 and highly associated with AIDS
- Four forms:
o Classic (older men)
o Endemic African
o Transplant-associated
o AIDS-associated
- Cutaneous lesions progress from patched to plaques to nodular tumors

- spindle cells forming slits with extravasated RBCs
- hemosiderin laden macrophages
- lymphocytes
- fibrosis
- minimal atypia


List 2 benign neural tumours.

1. Neurofibroma (nerve sheath)
2. Neuroma (nerve fibers and schwann cells)

Describe a neurofibroma.

- benign nerve sheath tumour
- mixture of schwann cells, perineural cells, fibroblasts, mast cells
- sporadic or related to neurofibromatosis
- 3 growth patterns
o superficial cutaneous neurofibroma - pedunculated
o diffuse neurofibroma – plaque like elevation of skin
o plexiform neurofibroma – nerve roots or large nerves


Describe a neuroma.

- benign non neoplastic overgrowth of nerve fibers and schwann cells
- usually post traumatic
- painful
- common subtypes:
o amputation or traumatic neuroma
o morton neuroma

Histology of amputation neuroma:
- irregular organization of nerve fibers immersed in scar tissue


How are lymphomas of the skin divided? Give two examples.

Divided loosely into B cell and T cell proliferation.

Mycosis fungoides = a cutaneous T cell Lymphoma
Primary Cutaneous Follicle Centre Cell Lymphoma = a cutaneous B cell lymphoma


Describe Mycosis fungoides.

- a cutaneous T cell Lymphoma
- elderly or adults
- skin-homing CD4+ T helper cells
- progression: patch, plaque, nodule/tumor
- often misdiagnosed early as eczema
- usually remains localized to skin for many years, but may evolve into generalized lymphoma


- may look similar to dermatitis – increased lymphocytes
- neoplastic lymphocytes form a band-like zone in upper dermis
- convoluted nuclear membrane – this would be unusual for dermatitis


Describe Primary Cutaneous Follicle Centre Cell Lymphoma.

- presents with solitary or localized skin lesions on the scalp, forehead or trunk
- erythematous plaques or nodules
- nodular diffuse pattern




1. Fat Tumors:

a. Lipoma = benign fat tumor
i. spindle cell lipoma
ii. chondroid lipoma
iii. pleomorphic lipoma
iv. angiolipoma

b. Liposarcoma = malignant fat tumor
i. atypical lipotamous tumour/well differentiated liposarcoma
ii. myxoid/round cell liposarcoma
iii. pleomorphic liposarcoma

2. Fibrous Tissue Tumors:

a. Dermatofibroma
b. Defmatofibrosarcoma protuberans (DFSP)
c. Atypical Fibroxanthoma (AFX)

3. Histiocytic Tumors:

a. Juvenile Xanthogranuloma (JXG)
b. Fibroepithelial polyp/skin tag/acrochordon (benign)

4. Smooth Muscle Tumors:

a. Leiomyoma (benign)
b. Leiomyosarcoma (malignant)

5. Blood Vessel Tumors:

a. Haemangiomas (benign)
i. capillary Haemangiomas
ii. juvenile Haemangiomas
iii. cavernous Haemangiomas
iv. lobular capillary Haemangiomas

b. Angiosarcoma (malignant)
c. Kaposi Sarcoma (malignant)

6. Neural Tumours:

a. Neurofibroma (benign)
b. Neuroma (benign)


1. T cell lymphoma:
Mycosis fungoides

2. B cell lymphoma:
Primary Cutaneous Follicle Centre Cell Lymphoma

Decks in Pathology-IMED4111 Class (88):