The patient
This 52-year-old lady presented with a reddish lump that she had noticed on her lower back for a month or two. It was painless and otherwise she felt well. She wasn't sure whether it had increased in size.
She had a significant past medical history including breast cancer – for which she had a lumpectomy six years ago – well-controlled diabetes, hypertension and asthma. Despite all this, she generally kept herself fit and usually only attended for her scheduled disease reviews. She was being prescribed metformin, amlodipine and salbutamol inhalers – none of which had been started recently.
First instinct
Examination revealed a small, reddish, ill-defined and non-tender lump on her lower back. The patient herself wondered if the lump was simply the effect of friction on her back. She had recently deliberately lost weight and was attributing the lump to her ‘bony spine' rubbing on the driver's seat of her new car. This seemed a plausible theory.
Differential diagnosis
• Local trauma
• Sebaceous cyst
• Dermatofibroma
• Pyogenic granuloma
• Diabetic skin complication
• Skin secondary
It's always tempting to collude with a patient's self-diagnosis. But certain aspects of this story didn't ring true. For one thing, she rarely attended, and so must have been concerned that this was more than a simple pressure effect. And for another, the lesion wasn't sore, which didn't fit with her theory.
Plenty of other skin lesions, such as sebaceous cysts, dermatofibromas and pyogenic granulomas look similar to this lesion. But none were a precise fit, because of its location and odd appearance.
Patients with diabetes are, of course, prone to a variety of skin complications, such as granuloma annulare and necrobiosis lipoidica. But again, her lesion wasn't typical of any of these.
That left a skin secondary from her breast carcinoma as a possibility – a differential I thought highly unlikely given its site well away from the original primary, and the fact she was so well.
The hidden clue
As I pondered the possibilities, she commented that it was odd that she still seemed to be losing weight despite having stopped dieting. Immediately, alarm bells rang.
Unexplained weight loss is always an ominous symptom in primary care, and the combination of this, her past history of breast cancer, and this difficult-to-explain skin lesion suddenly put disseminated carcinoma on top of the list.
Getting on the right track
Clearly, the next step was to get this lesion biopsied urgently. Sadly, this confirmed a skin metastasis from her primary breast cancer.
She is now under review by her oncologist to decide the best way forward – but, clearly, her prognosis is limited.
Dr Keith Hopcroft is a GP in Laindon, Essex
Skin metastasis from primary breast cancer Secondary skin metastasis
