The Half Decent Pharmaceutical Chemistry Blog

Now, it’s the summer, which means there’s a very simple way to recognize someone who is preparing exams at the moment: paleness. If someone is bronzed, it can’t be a student, that’s for sure. On the other hand, a pale, grey, autumnal skin colour usually stems from spending most of your day studying (unless you’re a multi-millionaire and can do it in the garden of you huge mansion: if that’s how things are, would you mind inviting me?).

Because I’m obviously among the latter, I want to be mean and chose to write a post about the danger of lying in the sun and skin tumours, in particular.

Basal cell carcinoma is probably the least severe skin cancer, considering its growth rate and the incredible low propensity to metastasise. Still, it’s the most common (75%) and can lead to clinically relevant outcomes, such as ulcerations or invasions of bone and facial sinuses.

The link with sun exposure, in this case, is particularly evident, as it develops mainly in lightly pigmented people (black people are almost completely immune) and only in those parts of the body which are highly exposed to sunlight.
UV-light, in fact, can easily damage DNA, yielding, for example, thymine dimers which are particularly vicious for a cell if its repair systems don’t recognize such a distortion.

Interestingly, while in the past its incidence was greatest in the seventh or eighth decade of life, these days (partly due to the increasing popularity of sun beds) people in their thirties and forties are subject to this tumour.

Histologically,  neoplastic basal cells exhibit either multifocal growth (spreading on the skin surface) or nodular, downward growth (affecting the inner dermal tissues).
Clinically, telangiectasia (spider veins) is a distinguishing feature, appearing in the red, smooth papules which grow on the skin.

Squamous cell carcinoma is extremely common in elderly people. Not only does UV-light play a key role, but industrial carcinogens, arsenic, ionising radiations and xeroderma pigmentosum have great importance too.

Histologically, cells in the epidermis look weird and prone to spread into the basement membrane, where they often are characteristically polygonal, as well as rounded, and undergo keratinisation (up to clinically relevant hyperkeratosis, which marks the moment the tumour reaches nodular stage).
5% of squamous basal carcinomas result in metastases, but that’s more due to the quick diagnosis rather than a characteristic of the tumour itself. Generally, sharp plaques are a clear sign of the development of this pathology.

Finally, malignant melanoma is the least frequent skin tumour (5%), but it’s the one linked to the highest risk of mortality and its incidence has doubled in the last twenty years.

Oncologists spotted a trend for what concerns the hereditary component of this disease: the CDKN2A gene, which encodes for a cyclin-dependent kinase inhibitor, is mutated or methylated in a vast number of patients with melanoma.

The tumour grows radially, in the beginning, within the epidermis. Then, a vertical growth starts and, at this stage, nodules form, metastases tend to appear (although not clinically yet) and the tumour reaches the reticular dermis.
Generally, these cancers develops at already-existing moles, changing their colour, enlarging them and creating irregular borders.

That said, I’m looking forward to the end of all this and to the beginning of my holidays…