March 2013

This gentleman presented with recent colour change in his thumb nail
King-man Ho ???

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Answer:
B. Nail psoriasis

The clinical photo showed a skin coloured nodule with surface almost like normal skin. Fibroepithelial polyp also known as skin tag is actually a pouching of skin. The neck, axilla and groin are sites of predilection. A patient may present with multiple lesions on these sites. Obese people may have higher prevalence of having the condition. Most people with skin tag are asymptomatic, some may claim that a few of the lesions catch on clothing leading to soreness. Physical examination reveals skin colourd or brownish pedunculated (with stalk) one to a few mm lesion with folded surface. In obese people, background of acanthosis nigrican may be present. Occasionally it may present as a solitary large pedunculated nodule as in this patient. The main differential diagnosis for the lesion shown in this clinical photograph is neurofibroma. Biopsy of this lesion confirmed that it is giant fibroepithelial polyp. The clue to differentiate the giant skin polyp from neurofibroma may be the very thin stalk (but not in this case) in the giant polyp and surface skin fold. Lipoma as the name infers is a benign tumour of the fatty tissue of the body. The subcutis is the most common site of occurrence. The shoulder, neck, and extensor surface of forearm are the sites of predilection. Lipomas are round to oval, soft, mobile nodules that lie between the subcutaneous layer and skin. As it may be embedded in the deeper part of skin, the margin is less well defined. The overlying skin is normal and is freely movable above a lipoma. It may sometimes felt bumpy/lobulated. The size ranges from a few centimeters to more than 10 cm. While most lipomas are asymptomatic, the variant angiolipoma is one of the well known differential diagnoses of painful skin tumours. Multiple lipomas can be present and alert one the possibility of hereditary condition like the Madelung’s disease. The clues to making the diagnosis may include the normal looking and movable overlying skin and location of the lesion at the subcutis. Dermal melanocytic naevus may present with skin coloured or light brownish/bluish dome shaped or papilloma like asymptomatic papule. Typically a lesion may start as a dark papule that over many years increases in size, remains stable and then fades in colour. Some patients may present with a skin colour small nodule at middle age. Physical examination reveals that the small nodule is soft to firm and sometimes with hair coming out the nodule. The clues to making the diagnosis may include history, evolution, the colour and the consistency. Solitary neurofibroma is a not uncommon benign skin tumour in young adult and the middle aged. About 10% may have more than one lesion that may arouse the attending clinician of the possibility of neurofibromatosis. Multiple lesions may sometimes occur along the course of a peripheral nerve. The mere presence of solitary or even multiple neurofibromata is not diagnostic of neurofibromatosis. A typical solitary neurofibroma may present as skin coloured or light tan soft sometimes pedunculated 0.2 to 2 cm or even larger nodule. Most patients are asymptomatic. Physical examination may reveal that the lesion is very soft, be easily invaginated and even be able to be pushed back into the dermis, this is known as the “buttonhole” sign. Plexiform neurofibroma is a subtype that may present as large soft plaque and when it is palpated, the “bag of worms” feeling may be revealed. The presence of multiple neurofibromata or plexiform neurofibroma should prompt the clinician to examine carefully for the other features of neurofibromatosis. Other cutaneous features of neurofibromatosis include café au lait macules, axillary or inguinal freckling. The other physical signs that can easily be detected in office include large head, scoliosis, mental retardation, hearing impairment, high blood pressure. Proactive treatment is not required for giant fibroepithelial polyp. If the clinician is not sure of the diagnosis or the patient request treatment, simple excision is good enough to remove the lesion most of the time. If the talk is thin enough, scissoring will be good enough to suturing.

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The slide and the question were prepared by:

Dr King-man Ho, ^{FRCP (Glasg, Edin), MRCP (UK), FHKCP, FHKAM (Medicine)}
Consultant Dermatologist-in-Charge,
Social Hygiene Service, PHSB, CHP, DH