Acanthosis Nigricans 

Acanthosis nigricans presents with areas of hyperpigmentation which have a velvety consistency typically around the skin flexures e.g., axilla.

Image Source: Wikimedia Commons (2020). Acanthosis Nigricans, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Acanthosis_nigricans.jpg (Accessed 23 May 2025).

Acanthosis nigricans is associated with the following conditions:

• Obesity 
• Non-insulin dependent diabetes mellitus 
• Polycystic ovarian syndrome
• Acromegaly 
• Cushing’s syndrome 
• Gastric malignancy 
• Lymphoma

Management

These lesions usually resolve with condition resolution. Active management with topical agents such as ammonium hydrate and vitamin D analogues are usually only required when this does not occur or when there are cosmetic difficulties.

Dermatomyositis

Dermatomyositis is an inflammatory myopathy with characteristic cutaneous manifestations. The condition is often linked to cancer.

Clinical features 

Approximately 80% of patients have myopathy, with patients exhibiting symmetrical, proximal muscle weakness. Dermatomyositis is, however, differentiated from polymyositis by the characteristic cutaneous signs:

• Gottron papules 
• Heliotrope oedema of the eyelids 
• Periungual telangiectasia 
• Poikiloderma
• Photo distributed erythema 
• Scaly alopecia
• Calcinosis cutis

Image Source: Wikimedia Commons (2018). Gottron Papules Dermatomyocitis, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/w/index.php?search=Gottron_papules_.dermatomyocitis.jpg&title=Special%3ASearch&profile=advanced&fulltext=1&ns0=1&ns6=1&ns12=1&ns14=1&ns100=1&ns106=1 (Accessed 23 May 2025).

Image Source: Wikimedia Commons (2017). Dermatomyocitis9, Licensed under a creative commons licence. Available for free at:  https://commons.wikimedia.org/wiki/File:Dermatomyositis9.jpg (Accessed 23 May 2025).

Dermatomyositis is associated with a 6 times increased risk of malignancy, with the following cancer types most reported:

• Ovarian
• Lung
• Pancreatic
• Breast
• Gastric
• Nasopharyngeal

Diagnosis

The diagnosis of dermatomyositis is complex with many criteria such as the “Bohan and Peter criteria” being proposed. In general, the following features are present:

• Symmetrical muscle weakness
• Elevation of muscle enzymes: High creatinine kinase levels is a sensitive but not a specific marker
• Presence of autoantibodies: in particular, Myositis Specific Antibodies being present in approximately 50% of all diagnoses
• Muscle biopsy evidence: Perivascular inflammation
• Cutaneous involvement
• Electromyographic/Magnetic resonance imaging evidence of disease activity

Management 

The mainstay management for dermatomyositis is with glucocorticoids. A dose of 1 – 1.5mg/kg/day of prednisolone is typically the initial treatment. Steroid sparing agents such as methotrexate may also be used.

In patients with a severe/refractory disease intravenous immunoglobulin is added.

Pyoderma Gangrenosum

Pyoderma gangrenosum is a rare neutrophil dominated skin disorder. It manifests with painful skin ulcers with irregular edges, often covered with a haemorrhagic exudate and excessive granulation tissue with slough. 

Associations 

Approximately half of patients with Pyoderma gangrenosum have an underlying disease. The most commonly associated conditions are:

• Inflammatory Bowel Disease (IBD)
• Inflammatory Arthropathies 
• Vasculitis 
• Haematological malignancies

Image Source: Wikimedia Commons (2002). Pyoderma Gangrenosum, Licensed under a creative commons licence. Available for free at: https://en.wikipedia.org/wiki/Pyoderma_gangrenosum (Accessed 23 May 2025).

Management

Treatment is challenging, typically relying on specialist input, with immunosuppressants used as a mainstay of treatment. 

When associated with IBD and haematological malignancies, Pyoderma gangrenosum will usually self-resolve with condition improvement. When still persisting, management includes good wound care and topical or systemic treatment.

Topical therapies centre broadly around topical corticosteroids. Whilst systemic therapy includes Ciclosporin which is often the first line systemic treatment, sulfasalazine, dapsone, sulphonamides and systemic corticosteroids. Biological therapies such as infliximab may be required in more severe or refractory cases. 

Good wound care is essential, and patients with particularly severe or poorly-healing lesions may require surgical debridement.

Erythroderma

Erythroderma is a dermatological emergency. It describes erythema and scaling of approximately 90% of the body total surface area. 

Aetiology 

Erythroderma can be categorised into congenital, infective, inflammatory, neoplastic, iatrogenic, and idiopathic causes. It is commonly present in pre-existing dermatological conditions such as psoriasis and eczema, with erythroderma occurring following sudden treatment cessation or the commencement of corticosteroids.

Causes

• Pre-existing psoriasis or eczema
• Spongiotic dermatitis 
• Corticosteroid commencement 
• Medication reactions
• T cell lymphoma

Complications

The onset of erythroderma puts the body into a catabolic state, leading to inflammation and increased heat loss. These processes can lead to the following complications:

• Cardiac failure – Due to increased cardiac output 
• Dehydration, Hypotension & Shock – Due to increased trans-epidermal water loss 
• Hypoalbuminemia – Due to desquamation in erythroderma 
• Skin infection

Management

The management of erythroderma is based on establishing the underlying cause and reversing/delaying that process e.g., stopping causative medication. 

Following this, the management is supportive e.g., restoring fluid balance +/- normal body temperature.

Dry sites can be managed with emollients and/or topical corticosteroids.

Neurofibromatosis 

Neurofibromatosis is a genetic condition which causes tumours on nervous tissues. There are three types: Neurofibromatosis Type 1, Neurofibromatosis Type 2 and Schwannomatosis, with their diagnosis being based on their clinical features.

Neurofibromatosis Type 1 (NF1)

This is by far the prevalent form of Neurofibromatosis, occurring in over 95% of cases. Its inheritance pattern is autosomal dominant, although 50% of cases are due to de novo mutations. 

Clinical Features 

The cardinal dermatological features of NF1 are:

• Café au lait patches
• Lisch nodules 
• Axillary freckling 

The diagnosis of NF1 is made when there are greater than six café au lait spots and skin tumours.

Image Source: Wikimedia Commons (2006). NF-1-Tache Café-au-lait, Licensed under a creative licence, Available for free at: https://commons.wikimedia.org/wiki/File:NF-1-Tache_cafe-au-lait.jpg (Accessed 23 May 2025).

Neurofibromatosis Type 2 (NF2)

This is less common than NF1. Its inheritance pattern is also autosomal dominant. Tumours typically arise on the Schwann cells. 

Clinical Features 

Neural tumours tend to arise with patients presenting with bilateral hearing loss and balance issues:

• Acoustic neuromas (bilateral)
• Meningiomas 
• Cutaneous neurofibromas

Image Source: Wikimedia Commons (2021). Neurofibroma in Neurofibromatosis, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Neurofibroma_in_neurofibromatosis_type_1.png (Accessed 23 May 2025).

Tuberous sclerosis 

Tuberous sclerosis is a rare multi-system autosomal dominant condition. Hamartomatous lesions characterise this condition. Whilst epilepsy (70%) and learning difficulties (50%) are common associations, the dermatological features are key in forming a diagnosis:

Dermatological features

• Hypomelanotic macules ≥ 3 at least 5 mm in size (seen in 90%) 
• Angiofibromas ≥ 3 (seen in 75%)
• Ungual fibromas ≥ 2 (seen in 20-80%)
• Shagreen patch (seen in ~50%)

Management

There is no cure for tuberous sclerosis, however, there are some treatments available for the dermatological manifestations of the condition. Sun protection should be advised, laser therapy may be useful for some patients, and mTOR inhibitors have been demonstrated to be effective in helping manage certain tuberous sclerosis variants.

Image Source: Wikimedia Commons (2007). Tuberous Sclerosis, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/w/index.php?search=tuberous+sclerosis+&title=Special%3AMediaSearch&go=Go&type=image (Accessed 23 May 2025).

Peutz-Jeghers syndrome

Peutz-Jeghers syndrome is an autosomal dominant condition characterised by multiple hamartoma polyps within the gastrointestinal tract and mucocutaneous pigmentation, particularly, on the lips.

Associations

• Hamartomas (most frequently in the small bowel)
• Small bowel obstruction (due to hamartomas)
• Gastro-intestinal bleeding 
• Intussusception 
• Gastro-intestinal cancer (unique hamartoma – adenoma – carcinoma pathway)

Management

There is no specific treatment for Peutx-Jegher syndrome. Management typically involves treatment of complications of the condition (such as removal of gastric or colonic lesions), and regular surveillance for conditions associated with the condition. This includes: gastrointestinal surveillance ± polyp excision, surveillance for extra-intestinal cancers such as; breast, testicular, pancreatic and lung cancer. Intense light therapy has been shown to be effective in treating the mucocutaneous pigmentation.

Image Source: Wikimedia Commons (2018). Peutzjegher Syndrome, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/w/index.php?search=PeutzJeghers&title=Special%3AMediaSearch&go=Go&type=image (Accessed 23 May 2025).

Gardner’s syndrome

Gardner’s syndrome is a condition of autosomal dominant inheritance. The condition has similar genetic variations on the adenomatous polyposis coli (APC) gene as seen in Familial Adenomatous Polyposis (FAP) and both are associated with an increased colorectal cancer risk.  

Clinical features

• Colon polyps
• Osteomas 
• Epidermoid or sebaceous cysts 
• Desmoid tumours

Multiple Endocrine Neoplasia (MEN) 2b  

MEN 2b is less common than MEN 2a. Its inheritance pattern is autosomal dominant. 

Clinical Features 

Unlike MEN 2a, it is associated with Marfan’s syndrome and ganglioneuromas:

• Phaeochromocytoma
• Medullary thyroid cancer 
• Marfan’s syndrome
• Neuromas around lips and tongue
• Ganglioneuromas of the bowel

Image Source: Wikimedia Commons (2019). Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Mucosal_Neuromas.png (Accessed 23 May 2025).

Von Hippel- Lindau syndrome

Von Hippel-Lindau (VHL) is an autosomal dominant inherited neoplastic disease occurring in approximately 1 in 360000 live births.

Clinical features

Patients typically present in their 20s with haemangioblastomas typically limited to the head and neck region:

• Central Nervous System haemangioblastomas (presents with symptoms pertaining to cord compression)
• Retinal angiomas (most common feature of VHL). Diagnosis usually confirmed following fluorescein staining (lesions show hyper-fluorescence) 
• Renal Cell Carcinomas 
• Phaeochromocytoma 
• Café au lait spots

Sturge-Weber syndrome

Sturge-Weber syndrome is a neurocutaneous disorder whereby a naevus flammeus affects the 1st two divisions of the trigeminal nerve (ophthalmic and maxillary).

Clinical features 

• A cutaneous naevus flammeus (port wine stain) is the characteristic sign of Sturge – Weber syndrome
• Leptomeningeal angiomatosis causing epilepsy (75 – 90%), hemiparesis (25-60%) and developmental delay (50-60%)
• Glaucoma (Occurring in 30-60%)

Image Source: Wikimedia Commons (2014). A new born child with M-CM Syndrome, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:A_new_born_child_with_m-cm_syndrome..png (Accessed 23 May 2025).

Wiskott-Aldrich syndrome

Wiskott-Aldrich is a rare X-linked recessive condition occurring in approximately between 1-10 in one million births. 

Clinical features

Wiskott-Aldrich is characterised by the clinical triad of:

• Thrombocytopenia
• Eczema 
• Immunodeficiency

Ataxia telangiectasia

Ataxia telangiectasia is an autosomal recessive condition whereby patients have defective DNA repair genes. Patients often have low levels of immunoglobulins e.g., IgA and IgG. 

Clinical features

The characteristic features of ataxia telangiectasia are: 

Ataxia, which is cerebellar in nature and first apparent in the toddler age group. Children demonstrate difficulties standing still and walking, with patients often requiring use of a wheelchair after the age of ten. 

Telangiectasia within the conjunctivae of the sclera or over the sun-exposed areas of the skin typically appear by the age of five. Other clinical features are seen below. 

• Learning difficulties 
• Chronic lung disease
• Lymphomas and leukaemias (~25%)
• Poor growth
• Infertility due to gonadal atrophy
• Dysphagia – Due to lack of coordination between mouth and pharynx

Investigations 

• Low immunoglobulin levels e.g. IgA and IgG
• Elevated Alpha- fetoprotein levels (~95% of patients)
• Cerebellar atrophy on MRI

Image Source: Wikimedia Commons (1968). Ataxia Telangiectasia, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Photo_Ocular_telangiectasia_in_a_person_with_A-T.jpg (Accessed 16 June 2025).

Dermatitis artefacta

Dermatitis artefacta is a factitious disorder. Patients intentionally damage their own skin and present with irregularly shaped dermatological lesions. The lesions often appear on normal surrounding skin, that is within easy reach.

The condition is often seen alongside other psychological/psychiatric conditions. Patients presenting are usually in early late puberty and of female gender. 

The diagnosis of dermatitis artefacta should only be made once other conditions have been excluded; in particular, pyoderma gangrenosum.

Image Source: Wikimedia Commons (2012). Dermatis Artefac, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/w/index.php?search=dermatitis+artefacta&title=Special%3AMediaSearch&go=Go&type=image (Accessed 23 May 2025).

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