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Skin and Soft Tissue Problems

Southwestern University College of Medicine

Problem-based and Distance Learning

Answers to Learning Issues

Submitted September 10, 1999 through email

Learning issue # 1 : Is bone a mesenchymal tissue?

Answers contributed by: Deanna Tapales Binoya

There are 2 types of embryonic tissue, the epithelial tissue and the mesenchymal tissue. The paragraph below differentiates each.

1. Epithelial tissue

- group of cells that are closely packed, with narrow intercellular clefts containing minimal extracellular materials

- cells usually show inter-cell surface specializations like desmosomes, tight junctions, gap junctions, etc.

- they clothe internal and external surfaces as simple or compound cellular sheets which separate phases of differing composition

- example: skin and mucous membranes

2. Mesenchymal tissue

- occupies all the regions between the various epithelial layers

- consists of loosely arranged tissue with wide spaces containing copious extracellular fluid which carries a variety of hydrated mucosubstances, suspended in which are scattered amoeboid, primitive mesenchymal cells

- origin:mesoderm,endoderm,cytotrophoblast

- differentiates into:

a. generalized specialized connective tissue (cartilage, bone, dentine) and their many types of attendant cell

b. smooth viscera, cardiac and striated muscle (somite)

c. endothelium of the blood and lymphatic vascular sys. and any attendant musculo- adventitial walls

d. various blood-forming sites, lymphoid tissue, bone marrow, spleen and the remaining elements of the reticolu-endothelial-macrophage system

e. tissue of the joints including their synovial cells and those of bursae and the tendon\ sheath

f. sheaths of nerves, muscles and the periostia of bones

Reference:

Gray's Anatomy 36th ed. by Williams et al. copyright 1989


Learning Issue 2: Clinical significance of the layers of Epidermis:

(Germ spin granny Luci's corn)

By Obriz M. Paglinawan

1. Stratum germinativum or stratum basale

- Mitotic figure occur frequently in this layer, thus producing new cells which are displaced into the layer above

- Grouped together with stratum spinosum as the malpighian layer (stratum [rete] malpighii). This layer is responsible for proliferation of the keratinization process.

- The malpighian layer also contains melanocytes, which produce the pigment melanin.

2. Stratum spinosum or prickle cell layer

- Responsible for the proliferation of the keratinization process.

3. Stratum granulosum

- Involved in the process of formation of soft keratin

- It is in this layer that the cell of the epidermis die.

- Contains membrane-coating granules or keratinocytes that function as a barrier to penetration by foreign materials, particularly water in both the deeper and more superficial layers but not in the central region of the stratum granulosum.

4. Stratum lucidum

- More apparent in the thick skin of palms and soles

- Consists of three to five layers of clear, flat, dead cells that contain droplets of an intermediate substance (eleidin) that is eventually transformed to keratin.

5. Stratum corneum

- Consists of 25-30 layers of flat, dead cells completely filled with keratin.

- Continuously shed and replaced by cells from deeper strata.

- Serves as an effective barrier against light, heat, bacteria, and many chemicals.

Reference:

Textbook of Histology 5th Ed. , Leeson et.al, W.B. Saunders company, 1985, pp. 291-297.

Histopathology of the Skin 7th Ed., J.B. Lippincott company, 1990, p. 9


Dear Dr. Joson:

For Claudelle's Learning Issue, we are very sorry that we can not give you the Prevalence on Skin Diseases because there are no records or clinical findings that we have gotten.

For the other learning issues, they will be sent perhaps tomorrow or by Monday.

If you have a message for us, just direct your e-mail to Herbert's e-mail address.

Thank you and Godspeed.

Obriz M. Paglinawan


Learning issue : Which skin cancer has the poorest and the best prognosis among basal cell carcinoma, squamous cell carcinoma, and melanoma?

Karen Zarandona

with best prognosis: BASAL CELL CARCINOMA

with poorer prognosis: MELANOMA

MELANOMA

- the most important prognostic factor: stage at the time of presentation

Five year survival for

a. clinical stage I and II : 80%; prognosis depends on the thickness of the primary tumor (see Table 1)

b. clinical stage III : 50% with only one node is involved ; 15-20% when four or more nodes are involved

c. clinical stage IV : <5%

 

Table 1. Prognosis of Melanoma by Thickness (Breslow) and AJCC Stages: 5 Year Survival Rates

AJCC Stage

Thickness range,mm

% Overall survival

IA (localized)

< or = 0.75

96

IB (localized)

0.76 - 1.50

87

IIA (localized)

1.5 - 2.49

75

2.5 - 3.99

66

IIB (localized)

> or = 4.00

47

III (metastatic to regional nodes)

45(1 node)

<20(2 nodes)

IV(metastatic to distant sites)

8-10 with 1 year survival

BASAL CELL CARCINOMA

- a slowly enlarging, locally invasive neoplasm

- degree of local destruction and risk of recurrence vary with the size, duration, and location of the tumor, the histologic subtype, the presence of recurrent disease, and various patient characteristics

- metastatic potential: 0.0028 to 0.1 percent

- with a higher risk when located on central face, ears, or the scalp

SQUAMOUS CELL CARCINOMA

- have the ability to metastasize, accounting for most of the 2300 deaths annually

- tumors arising on actinically damaged skin have a lower metastatic potential than those of protected surfaces

- metastatic frequency of cutaneous SCC : 0.3 - 3.7%

- metastatic potential of tumors occuring in lower lip and ear: 13 and 11% respectively

- metastatic potential arising in burn scars, chronic ulcerations, or the genitalia is higher

- overall metastatic rate for recurrent tumors: 30%

- most common site of metastasis: regional lymph nodes

- with metastatic disease, 5-year survival rate may be low

Reference:

Harrison's PRINCIPLES OF INTERNAL MEDICINE, 14th ed. by Fauci et al., copyright 1998


Pain Pathway by Lilibeth Macarine


PBL and Distance Learning on Skin and Soft Tissue Problems

Overview and Personal Perspective on the Health Problem

Hypothetical Patient Management

Evaluation - Written Objective Exam

Evaluation - Essay Exam - Written Practical Exam

End-of-Course Students' Assessment

Students' Evaluation of Course

 


SWU-MHAM-CM