Spreading Rash on Shin: What Does it Signify?
Mr. M is a 42-year-old patient that presented for evaluation and management of a skin rash on his left shin. The rash had been present for four weeks, and initially occurred after the patient bumped into an open dishwasher door. At first he thought it was just a bruise, but the rash continued to linger.
During the time since the patient's injury, his teenage son -- who competed in wrestling -- was diagnosed with tinea corporis. Mr. M was heavily involved with his son's meets, competitions, practice and training. Mr. M stated he wanted the same cream his son was using, as his rash was almost clear.
Mr. M took no other medication and last saw a healthcare provider two years ago for an upper respiratory infection. Before the last acute care visit, the patient's previous visit occurred more than two years before, when his wife persuaded him to make an appointment for a physical.
Mr. M was Hispanic and worked as a computer programmer. His blood pressure was 140/90. Patient height was 5'10” and weight was 182 lbs. When last checked four years previously, the patient's cholesterol levels were on the upper end of normal.
Physical examination of the left shin revealed a 2 cm brownish, red, annular plaque, where the patient indicated he was traumatized with the dishwasher door. He had diffuse dryness and flaking on both legs and elbows. Multiple toenails were thick and yellow. Heart, lung and abdomen examination was normal. No adenopathy was present.
You diagnosed the patient's toenail condition as onychomycosis, and asked if he would want to use oral or topical anti-fungal therapy. He declined and said he hated taking medication and that his nails do not bother him.
Given the family history of tinea corpus, you prescribed the patient the same topical anti-fungal as his son, recommended OTC topical ammonium lactate for the generalized xerosis, and scheduled a follow-up physical examination in six weeks.
The patient returned after four months and reported he used the cream but it had not helped. The rash seemed to be spreading and there was ulceration in one area. Physical examination revealed a 6 cm plaque on the patient's left shin.
The lesions appeared more shiny and atrophic in appearance. There were also two similar brown plaques on his right shin. The patient said the rash did not itch or hurt him, but he did not like the way it looked. Diffuse scaling was still present.
After a biopsy was performed, the pathology report indicated the presence of interstitial and palisaded granulomas that involved the subcutaneous tissue and dermis. The granulomas were dense with multinucleated histocytes and were consistent with a diagnosis of necrobiosis lipoidica.
Further laboratory testing revealed the patient had a hemoglobin A1c level of 7.2, a fasting blood sugar of 165, total cholesterol of 280 mg/dL, low density lipoprotein of 140 mg/dL, high density lipoprotien of 52 mg/dL and a triglyceride level of 246 mg/dL.