A. Bullous pemphigoid
B. Cutaneous lichen planus
C. Dermatitis herpetiforms
D. Eczema
E. Porphyria cutanea tarda
6. Which one of the following factors is most important in determining the prognosis for a patient diagnosed with malignant melanoma?
A. Depth of invasion in the skin and cutaneous tissue
B. History of pigmented naevus
C. Absence of pigmentation
D. Number of mitotic figures in the microscopic specimen
E. Ulceration of the primary melanoma
7. A 58-year-old woman with a long-standing history of type 2 diabetes and hypertension presents with a rash on her leg that in the past few months has progressively worsened. Her most recent HbA1c is 9.2% and she also has both chronic kidney disease and retinopathy. On physical examination, the rash shown below is observed on her shin. What is the most likely diagnosis in this patient?
A. Acanthosis nigricans
B. Necrobiosis lipoidica
C. Erythrasma
D. Contact dermatitis
E. Plaque-type psoriasis
8. A 27-year-old man develops a reddish brown macule on his face soon after taking a trimethoprim–sulphamethoxazole tablet for urinary infection. The lesion heals over the next few weeks with hyperpigmentation. He had a similar lesion on his face 3 years ago after exposure to trimethoprim–sulphamethoxazole. What is the most likely diagnosis?
A. Discoid lupus
B. Fixed drug reaction
C. Pemphigus vulgaris
D. Atopic dermatitis
E. Pityriasis rosea
9. A 36-year-old woman has redness and itching of the hands with tiny vesicles, scaling and fissuring, accompanied by itching on the palms. A diagnosis of hand eczema has been made, but simple emollients have not improved matters. Which one of the following agents is NOT used for the treatment of severe hand eczema?
A. Topical glucocorticoids
B. Topical tacrolimus
C. Oral retinoids
D. Oral ciclosporin
E. Hydroxychloroquine
10. A 56-year-old woman who had received a kidney transplant 5 years ago presents with a 4-day history of painful lesions on the anterior surface of both legs, as shown below. On examination the lesions are firm and tender. A biopsy shows panniculitis involving inflammation of septa in the subcutaneous fat tissue without any evidence of vasculitis. What is the most likely diagnosis?
A. Systemic lupus erythematosus
B. Fungal infection (tinea corporis)
C. Pyoderma gangrenosum
D. Erythema nodosum
E. Pretibial myxoedema
Answers
Basic Science
1. Answer A
Melanoma is a molecularly heterogenous malignancy. Systematic genome-wide screening has identified missense mutations in the B-raf gene, a component of the mitogen-activated protein kinase (MAPK) pathway in 66% of melanomas. An additional 15–20% of melanomas contain activating mutations in N-ras, a component of the MAPK pathway upstream of B-raf. These mutations are present in the majority of melanomas arising on skin intermittently exposed to the sun. B-raf and N-ras mutations in melanoma suggest that pharmacological inhibition of the MAPK pathway may provide therapeutic benefit. Inhibitors of the MAPK pathway are currently undergoing clinical investigation with some recent promising results (Sausville, 2012). Metastatic melanoma remains an aggressive malignancy conferring a very poor prognosis and standard chemotherapy has not demonstrated an overall survival benefit.
Melanoma is a molecularly heterogenous malignancy. Systematic genome-wide screening has identified missense mutations in the B-raf gene, a component of the mitogen-activated protein kinase (MAPK) pathway in 66% of melanomas. An additional 15–20% of melanomas contain activating mutations in N-ras, a component of the MAPK pathway upstream of B-raf. These mutations are present in the majority of melanomas arising on skin intermittently exposed to the sun. B-raf and N-ras mutations in melanoma suggest that pharmacological inhibition of the MAPK pathway may provide therapeutic benefit. Inhibitors of the MAPK pathway are currently undergoing clinical investigation with some recent promising results (Sausville, 2012). Metastatic melanoma remains an aggressive malignancy conferring a very poor prognosis and standard chemotherapy has not demonstrated an overall survival benefit.
Sausville, E.A. (2012). Promises from trametinib in RAF active tumors. N Engl J Med 367, 171–172.
2. Answer A
Sunburn and direct damage to DNA is caused by ultraviolet B (UVB) radiation, but ultraviolet A (UVA) may be more damaging to the skin by free radical generation, photoageing, immunosuppression and photocarcinogenesis (Berwick, 2011). Terrestrial UV radiation consists of 5% UVB, which is mostly absorbed by the epidermis, and 95% UVA which can penetrate below the dermis.
Sunscreens may be organic or inorganic chemicals and should ideally block both wavebands, UVA and UVB. The sun protection factor (SPF) is mainly based on the effectiveness of the sunscreen in blocking UVB. It does not measure the effectiveness against UVA. It is determined by a highly controlled clinical test using lamps that simulate solar radiation on human volunteers. It measures the time taken for a minimal erythema to appear when sunscreen is applied compared to without sunscreen. Therefore, an SPF of 15 means that it takes 10 min for skin to start to burn without sunscreen compared to 150 min with that sunscreen. Sunscreens that have identical SPF ratings will have equal protection against UVB under the controlled conditions that are used to determine the SPF. One long-term study has found that regular use of sunscreen by adults can prevent the development of pre-cancerous actinic keratoses and skin cancers (squamous cell carcinoma and melanoma). While basal cell carcinomas (BCCs) did decrease, the results were not statistically significant, possibly because BCCs result from damage caused early in life.
Sunburn and direct damage to DNA is caused by ultraviolet B (UVB) radiation, but ultraviolet A (UVA) may be more damaging to the skin by free radical generation, photoageing, immunosuppression and photocarcinogenesis (Berwick, 2011). Terrestrial UV radiation consists of 5% UVB, which is mostly absorbed by the epidermis, and 95% UVA which can penetrate below the dermis.
Sunscreens may be organic or inorganic chemicals and should ideally block both wavebands, UVA and UVB. The sun protection factor (SPF) is mainly based on the effectiveness of the sunscreen in blocking UVB. It does not measure the effectiveness against UVA. It is determined by a highly controlled clinical test using lamps that simulate solar radiation on human volunteers. It measures the time taken for a minimal erythema to appear when sunscreen is applied compared to without sunscreen. Therefore, an SPF of 15 means that it takes 10 min for skin to start to burn without sunscreen compared to 150 min with that sunscreen. Sunscreens that have identical SPF ratings will have equal protection against UVB under the controlled conditions that are used to determine the SPF. One long-term study has found that regular use of sunscreen by adults can prevent the development of pre-cancerous actinic keratoses and skin cancers (squamous cell carcinoma and melanoma). While basal cell carcinomas (BCCs) did decrease, the results were not statistically significant, possibly because BCCs result from damage caused early in life.
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