Rosacea is a common facial rash. It is characterised by sterile inflammatory papules, pustules, and nodules that may sometimes be mistaken for acne vulgaris, but do not cause comedones. It is associated with the mite Demodex folliculorum, which is a…
Vitiligo is an autoimmune condition that is characterised by depigmentation of the skin due to loss of melanocytes. It affects 1% of the population. The peak incidence is 20 – 30 years. It affects men and women almost equally.
Melanoma is the proliferation of atypical melanocytes. It is the most dangerous type of skin cancer. Melanoma has a high potential to invade the dermis and metastasise. 70% of melanoma arises from normal skin, while 30% arise from pre-existing naevi.…
Lichen planus is a chronic, inflammatory, pruritic skin condition. It is characterised by an itchy papular rash commonly on the palms, soles, genitalia, or flexor surface of the arms. It is a T-cell-mediated autoimmune disorder. The diagnosis is clinical. It…
Definition of terms Term Definition Adverse drug reaction (ADR) A noxious and unintended response to medicine that occurs at normal therapeutic doses used in humans for prevention, diagnosis, or therapy of disease, or for the modification of physiologic function Side…
A 52-year-old woman presents with a 3-month history of a painless lump in her left breast. Biopsy confirms invasive ductal carcinoma, stage II (T2N1M0). She undergoes breast-conserving therapy (lumpectomy with sentinel lymph node biopsy). Post-operatively, she is referred to the…
A 45-year-old woman with breast cancer on adjuvant chemotherapy presents with a fever of 38.9°C, chills, and malaise. She looks acutely unwell. On physical examination, she has hypotension (BP 90/60 mmHg), tachycardia, with no localising source of infection. Her laboratory…
Overview Purines are nitrogen-containing heterocyclic bases that form part of nucleotides. They have a double-ring structure (6-membered ring fused to a 5-membered ring) Precursors for de novo purine ring synthesis Precursor Contribution Glycine C4, C5, N7 Glutamine N3, N9 Aspartate…
Tetrahydrofolate (THF) is essential for purine synthesis and thymidylate (dTMP) formation, both of which are important for DNA synthesis. THF synthesis in Bacteria vs Humans Category Description Bacteria Must synthesize folate de novo Humans Cannot synthesize folate de novo. Folate…
A 42-year-old woman presents to the outpatient clinic with a 6-month history of joint pain and stiffness. The pain initially started in the small joints of her hands and has progressively worsened. She describes morning stiffness lasting more than an…