The Pharmacist is most likely to be consulted about stasis eczema, lichen simplex chronicus and psoriasis if it is a red scaly rash. Pigment changes around the ankles from leaky varicose veins might also be presented. An acute cellulitis in a diabetic would be the most worrying presentation to correctly diagnose and refer for treatment
The main solar lesions you will see on the lower legs are solar
keratoses, SCC in situ, and occasionally melanoma particularly in women, but
there are a variety of medical conditions that can affect the lower legs and
present as lumps as well.
Examples of
this include hypertrophic lichen planus (GSA) particularly on the anterior
shins. It will have a purple colour with
surrounding pigmentation but the nodules can be quite significant and can
simulate a squamous cell carcinoma.
 |
| Hypertrophic lichen planus Note color and Wickham's striae |
Lichen simplex chronicus (GSA) can affect the lower legs as well, and again give rise to
nodules, but this time we call them prurigo nodules. These can look very similar to
keratoacanthomas but usually have a much longer duration and dont have a true keratin core. KA’s erupt quickly.
 |
| Lichen simplex chronicus with prurigo nodule |
The lower leg is a site of
chronic lymphedema. (Dermnet) It is also the site
of stasis. Chronic lymphedema can be
congenital or it can be acquired. The
congenital version is known as Milroy’s disease, and these patients are very
susceptible to infection but also they get overlying thickened changes in
the epidermis with time that makes them susceptible to cellulitis.
Stasis dermatitis is something you will see
in a lot of lower legs. It is due to
venous hypertension. There can be
weeping and scarring, and if there is a lot of scarring it goes under the name
of Lipodermatosclerosis or atrophie blanche. Generally the skin
here is very thick. It is difficult to
do excisions, and most surgical procedures end up requiring skin grafts. These patients will generally have to be in
hospital with their legs elevated and some degree of negative pressure device
applied to allow the skin graft to take.
 |
| Stasis dermatitis |
 |
| Atrophie Blanche |
A curious
phenomenon you may see just around the ankle beneath the medium malleolus are
small hernia like protrusions known as piezogenic papules. This is just a pressure phenomenon of mild
herniation of the underlying fascia or fat, and it is of no significance. The lesions certainly don’t need to be
biopsied or removed.
 |
| Piezogenic papules foot |
Pigment changes in
the lower leg are quite common especially in stasis, but the pigment in this
case is due to hemosiderin not melanin.
It is due to pinpoint haemorrhage from capillaries in the skin due to
increased venous pressure and capillary pressure. It is more prominent on people who are on
blood thinners. It goes under the name
of pigmented purpuric dermatosis. (GSA) (Dermnet) Some
of these can take an annular pattern.
Some can look a golden orange colour and are called lichen aureus, but
they are all basically due to hemosiderin from capillary leakage. If the capillary leakage can be decreased by
support stockings then the pigmentation will slowly fade over six months or
more.
 |
| Pigmented purpuric dermatosis |
 |
| Lichen aureus |
Other
medical conditions commonly occurring on the lower legs anteriorly include
erythema nodosum. (GSA) This usually follows a
streptococcal throat infection or a female coming off the contraceptive pill,
but occasionally it can be a manifestation of sarcoidosis so a chest x-ray
should be ordered if you diagnose this condition. The
lesions represent a septal paniculitis, in other words it is inflammation in
the septae between the lobules of fat, so it is deep in the skin. There may be slight leakage of red blood
cells since a small degree of bruising can be seen around the lesions which are
usually tender, and on the anterior shins. Rx with rest and non-steroidal anti-inflammatories and support
bandaging.
 |
| Erythema nodosum |
Other medical conditions seen along the front
of the shins include necrobiosis lipoidica, (GSA) particularly in diabetics. It has a very characteristic location over
the underlying tibial plate. It has a
yellowish look to it because of the overlying epidermal atrophy, and often
shows the prominent blue veins underlying it.
It is important not to biopsy the centre of this but to biopsy the edge
if you are going to. It is a difficult
condition to treat. If patients injure
or ulcerate this area it can be slow to heal.
Rx There aren’t any good treatments.
You try and just get their diabetes under better control. You can try a little bit of diluted intralesional
steroid into any new lesions that come up.
The earlier you are able to get them the more effective the intralesional
steroid is in treatment.
 |
| Necrobiosis lipoidica |
A patient
may have a linear lump under the skin in the lower legs and this usually a
superficial thrombophlebitis with a recent injury. Generally these will slowly resolve on their
own. There is usually no deep venous
involvement.
Ulcers in
the lower leg are the classic venous ulcer over the medium malleolus, the
arterial ulcer that is punched out, and the neuropathic ulcer typically on the
soles of the feet and more prominent in diabetics.
 |
| Venous stasis ulcer |
 |
| Arterial ulcer |
 |
| Neuropathic ulcer |
 |
| Radionecrotic ulcer |
 |
| Ulcerated SCC |
 |
| Early arterial ulcer |
The lower
leg is a common site for dermatitis.
Usually it is a stasis dermatitis.
Occasionally it can be an allergic contact dermatitis that people have
been applying, so always take that into account when you are assessing
reactions around ulcers. Make sure you
know what the patient has put on them.
Discoid eczema is also common on the lower legs. It is a red scaly itchy patch with small surface erosions and slight crusts if infected. Psoriasis is a differential but it does not have the small ewrosions of eczema or the crusts.
Rx Discoid eczema is treated with a strong topical steroid and topical Mupoirocin for any secondary infection. Psoriasis plaques are best treated with Enstilar foam applied daily until cleared then as required for flares.
 |
Infected dermatitis legs Contact superimposed
|
 |
| Patch of weeping discoid eczema |
 |
| Severe plaque psoriasis leg |
 |
| Psoriasis or Eczema? |
