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Tag Archives: non melanoma skin cancer

Lack of UV-A Protection In Daily Moisturising Creams


Came across another interesting article in the May edition of ‘The Archives of Dermatology’ 2011. The article is entitled ‘Lack of UV-A Protection In Daily Moisturising Creams’ on page 618.

Ultraviolet radiation (UV) contains UVA, UVB and UVC subtypes. The major source of UV exposure for humans is sunlight. The earths ozone layer blocks approximately 98% of all UV radiation and the 2% which reaches the earths surface 99% is of the UVA subtype. UVB can cause direct DNA damage whereas UVA causes indirect damage of DNA via the formation of free radicals. Therefore it is important any sunscreen solution contains both UVA and UVB filters.

This article reported the estimated long-range UVA1 protection of 29 creams.

Major points of note from the article include

– most daily facial creams contain ingredients known as UV filters claiming broad spectrum UV protection

– Sun protection factor (SPF) doesn’t reflect UV-A1 protection

– UVA penetrates window glass whereas UVB is blocked, therefore women working indoors need to protect themselves from UVA exposure

– of the 29 creams 6 didn’t contain any UVA1 filters

I recommend reading the full article as it is an interesting read. Below is a link to the article.

Lack of UV-A Protection in Daily Moisturizing Creams
Steven Q. Wang; Jacqueline M. Goulart; Henry W. Lim
Arch Dermatol. 2011;147(5):618-620

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Persistent Melanocytic Nevi: A Review and Analysis of 205 cases


Great article in the June 2011 issue of the ‘Journal of Cutaneous Pathology’ regarding persistent melanocytic naevi. Good reading for those interested in the subject.

Things of note are

– female predominance (reason unclear)

– back is the most common site followed by abdomen then chest

– mean time between original biopsy then biopsy of persistent naevus was 9.7 months

– dysplastic naevi were most likely to recur

– persistent melanocytic naevi were more likely to be initially removed via shave biopsy

 

Link to the article below

http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0560.2011.01692.x/abstract

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Melanoma Research – Sex differences in survival of cutaneous melanoma are age dependent


Came across an interesting article in the latest issue of the Melanoma Research journal regarding differences in survival rates based on sex. It has been previously observed that women have a better survival rate for melanoma than men. This has also been observed in other cancers such as lung adenocarcinoma and colon cancer.

The study reveals that the slight survival benefit women with melanoma experience, disappears after the age of 60. This is mirrored, but also conflicts with other studies referenced within the article.

Proposed reasons for this female survival benefit include women being more prudent in the personal examination of the skin, women having a greater percentage of lower limbs melanomas which are associated with a better prognosis and immune gender differences.

Below is a link to the article abstract

http://journals.lww.com/melanomaresearch/Abstract/2011/06000/Sex_differences_in_survival_of_cutaneous_melanoma.11.aspx

 I recommend getting the whole article if it is possible.

 Thanks for reading and I welcome any comments.

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Periodic-Acid Schiff (PAS) Special Stain – Method and Tips


The Periodic-Acid Schiff (PAS) technique (and its numerous variations) is by far the most commonly performed special stain within the histopathology laboratory, therefore knowledge of its method is a vital arrow in any medical scientist’s quiver of knowledge.

The PAS technique is most commonly used to highlight molecules with a high percentage carbohydrate content such as mucins, glycogen, fungi and the basement membrane in skin.

The PAS method works by exposing the tissue to periodic acid. This acts an oxidizing agent which oxidizes vicinal (neighbouring) glycol groups or amino/alkylamino derivatives. This oxidation creates dialdehydes.These dialdehydes when exposed to Schiff’s reagent create an insoluble magenta compound which is similar to the basic fuchsin dye within the Schiff’s reagent.

SOLUTIONS

Schiffs reagent

1% aqueous periodic acid

METHOD

1. Take sections to water.

2. Expose sections to periodic acid solution for 10-15 mins.

3. Rinse well in tap water.

4. Expose sections to Schiff’s reagent for 10-15 mins.

5. Wash in running tap water for 5-10 mins

6. Counterstain with a haemtoxylin for approx. 15 secs.

7. Differentiate (if necessary) and blue.

8. Dehydrate, clear and mount.

TIPS

– Periodic acid and Schiff’s reagent are easily available commercially prepared, the technique for self-made Schiff’s reagent is arduous by comparison but can be found.

– Keep your Schiff’s reagent out of UV light and refrigerated when not in use. Failure to do so will result in the loss of sulphur dioxide in your Schiff’s reagent leading to the solution turning from colourless to a magenta colour resembling the original basic fuchsin colour. When this happens replace your solution. Also keep your periodic acid solution refrigerated when not in use.

– The purpose of washing in running tap water after exposing the sections to Schiff’s is to intensify the magenta colour. This author has found that when the water has runs from a magenta colour to a clear colour the colour isn’t going to intensify any further therefore the washing in running water can be ceased. This may vary from lab to lab.

– There are numerous variations of the PAS technique (eg. PAS + diastase, PAS + Alcian Blue). This will be discussed in a further blog post.

 Below is a PAS stain of a section of skin from the scalp.

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Alcian Blue Stain For Acidic Mucins – Method and Tips


The alcian blue stain is this author’s preferred stain for the demonstration of acidic mucins. The dye was originally used for the dyeing of cotton before being discovered as a by Steedman in 1950.

The alcian blue itself is a cationic copper phthalocyanine dye which stains mucopolysaccharides and glycosaminoglycans a bluish colour. Within skin, acidic mucins can be found in many differing conditions such as a mucinoma, lupus and alopecia mucinosa.

Below is the preferred alcian blue method of this author

METHOD

Solutions

1g alcian blue in 3% acetic acid (check pH = 2.5)

1% safranin

1. Take sections to water

2. Cover slide with FILTERED alcian blue solution and leave for 20 minutes

3. Rinse in tap water

4. Counterstain with FILTERED 1% safranin for 10-15 seconds

5. Rinse in tap water

6. Dehydrate quickly, clear and mount.

Tips

– this author prefers an alcian blue staining time of about 20 minutes but can be done within the range of 10-30 minutes if desired.

– by reducing the pH to 0.2 the stainer can select for only strongly sulphated mucins. A pH of 1.0 stains both weak and strongly sulphated mucins. If using a lower pH method be sure no to rinse in tap water between the steps for too long as this can affect the alcian blue staining.

– this author prefers safranin as a counterstain due to its crisper staining, but safranin leeches out quickly in the dehydrating alcohols therefore blot dry after counterstaining and quickly dehydrate through the alcohols.

– neutral red can also be used as a counterstain.

– the alcian blue staining solution expires after approximately 6 months.

Thanks for reading and I welcome any comments and other tips.

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Cutaneous Squamous Cell Carcinoma – Overview


Squamous cell carcinoma (SCC) is defined by the World Health Organisation as ‘a malignant neoplasm of epidermal (and mucous membrane) keratinocytes in which the component cells show variable squamous differentiation.’

Most SCCs appear on the areas of the skin which get the most sun exposure though this is not the only place which the can arise. SCCs can also arise on mucosal areas such as on the lip. Patients who have a pale complexion and those who do not tan readily are at a greater risk. SCC is very uncommon in the Black population.

The most important causative agent is sun exposure, more correctly UVB radiation. Others factors that have been incriminated include human papilloma virus (HPV) infection, ulcers, immunosuppression and radiotherapy. Patients with organ transplants are also at a greater risk. SCC can be fatal in some cases (most commonly found in Australia) giving rise to the notion that sun exposure, which causes DNA damage and also suppresses the skin immune system, plays a lead role in the cause of aggressive SCCs.

As sun exposure is the major cause factor of SCC, it is no surprise that the forehead, ears, scalp, face, neck, back of the hands and lips are the most common places to find SCCs on the human body.

SCCs commonly appear as plaques/nodules with an elevated/indurated, crusty surface. The areas immediately surrounding the SCC show the typical signs of sun damage.

I have previously blogged about the prognostic factors of SCC, please click on the link to see more (Prognostic Factors of Cutaneous Squamous Cell Carcinoma)

Thanks for reading and I welcome any comments.

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Superficial Basal Cell Carcinoma – A closer look


Superficial basal cell carcinoma (SBCC) is a growth pattern of basal cell carcinoma (BCC) which accounts for approximately 10-30% of all BCCs.

CLINICAL

SBCC presents typically as a reddish (erythematous) patch ranging in size from approximately 3 to >10 mm. They often have a fine pearly border with central superficial erosions. Pale areas within the lesion can be a clue to regression and the lesion may have a history of bleeding. SBCCs are most commonly found on the trunk.

HISTOPATHOLOGY

SBCC is seen as superficial collections of atypical basaloid cells originating from the bottom layer (basal layer, stratum basale) of the epidermis and projecting down into the papillary dermis. These collections are typically surrounded by a loose myxoid (mucin-like) stroma. Although histologically they have an apparent multifocal appearance recent 3D imaging techniques have found that a huge majority of these foci are truly interconnected and therefore not multifocal. Remember SBCC is also usually seen in conjunction with other BCC growth patterns such as nodular and infiltrative.

PROGNOSIS AND TREATMENT

Due to its superficial nature, SBCC has a very good prognosis and there is a wide range of treatments available. SBCC does have a high recurrence rate due to its margins being difficult to assess (this is attributed to its apparent multifocal appearance histologically). Treatments include topical chemotherapy (eg. aldara), photodynamic therapy (PDT) and curettage.

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