Erysipelas as a sign of subclinical primary lymphoedema: a prospective quantitative scintigraphic study of 40 patients with unilateral erysipelas of the leg

ABSTRACT

Background Erysipelas is a common skin infection that is usually caused by β-haemolytic group A streptococci. After having had erysipelas in an extremity, a significant percentage of patients develops persistent swelling or suffers from recurrent erysipelas. We hypothesize that in cases of erysipelas without a clear precipitating agent, subclinical pre-existing congenital or acquired disturbances in the function of the lymphatic system are present. The persistent swelling after erysipelas is then most likely caused by lymphoedema.

Objectives We designed a study to examine if erysipelas of unknown origin is associated with a pre-existent insufficiency of the lymphatic system. If our hypothesis is correct, patients with erysipelas of unkown cause without previously evident lymphoedema should have evidence of disturbed lymphatic transport in the unaffected extremity.

Methods A prospective study, in which lymphoscintigraphy of both legs was performed in patients 4 months after presenting with an episode of erysipelas only in one leg. No patient had any known risk factor for erysipelas, such as diabetes mellitus, chronic venous insufficiency or clinical signs of lymphoedema. Lymphoscintigraphy was performed in 40 patients by subcutaneous injection of Tc-99m-labelled human serum albumin in the first web space of both feet. After 30 and 120 min, quantitative and qualitative scans were performed using a computerized gamma camera. During the lymphoscintigraphy, the patients performed a standardized exercise programme. Lymph drainage was quantified as the percentage uptake of Tc-99m-labelled human serum albumin in the groin nodes at 2 h after injection. Groin uptake of < 15% is pathological; uptake between 15–20% is defined as borderline, and uptake of > 20% as normal.

Results The mean ± SD percentage uptake in the groin nodes in the affected limbs was 9·6 ± 8·5% vs. 12·1% ± 8·9% in the nonaffected limbs. The mean paired difference in uptake between the nonaffected vs. affected side was 2·5% (95% confidence interval 1·1–3·9%). This indicates that lymphatic drainage in the nonaffected limb was only slightly better than in the affected limb despite the infectious event in the latter. Of 33 patients with objective impairment of lymph drainage in the affected limb, 26 (79%) also had impaired lymph drainage in the nonaffected limb. Agreement in qualitative measurements between affected and nonaffected leg was less pronounced: 21 patients had abnormal qualitative results in the affected leg of whom nine also had impairment of the nonaffected leg (43%).

Conclusions Erysipelas is often presumed to be purely infectious in origin, with a high rate of recurrence and a risk of persistent swelling due to secondary lymphoedema. In this study, we show that patients presenting with a first episode of erysipelas often have signs of pre-existing lymphatic impairment in the other, clinically nonaffected, leg. This means that subclinical lymphatic dysfunction of both legs may be an important predisposing factor. Therefore, we recommend that treatment of erysipelas should focus not only on the infection but also on the lymphological aspects, and long-standing treatment for lymphoedema is essential in order to prevent recurrence of erysipelas and aggravation of the pre-existing lymphatic impairment. Our study may change the clinical and therapeutic approach to erysipelas as well as our understanding of its aetiology.