Madura's foot: report of a case caused by Madurella mycetomatis

ARTICLE

Mycetoma is a skin located, slow growing infection, clinically characterized by a thick and swollen lesion with sinuses draining a purulent exudate containing granules. Frequently encountered in tropical countries, this infection is exceptional in our latitudes and only a few cases have been reported [1-3]. Etiologically two different groups of microrganisms are involved: i) bacteria belonging to the group of Actinomyces (microaerofila, gram⁺); ii) true mycetes; the latter give origin to the lesion named "eumycetoma" [4, 5]. In the case of mycotic aetiology the more frequent localization on the foot is the reason for the term "Madura's Foot" (from the name of the Southern Indian town where the infection was initially observed and described) [5, 6].

We report a case of mycetoma caused by Madurella mycetomatis. This is a polymorphic, saprophytic mould in the ground, which appears at microscopic observation as colonies characterized by a typical grainy formation in appearance, closely resembling "granules of sulphur". This is also a typical morphological feature of Actinomyces colonies [5, 6].

The exceptional occurrence of this disease in our latitudes and the absence of a clear infectious picture was the reason for an initial clinical misinterpretation as a vascular neoplastic lesion. Only the histological examination gave a clear-cut diagnosis.

Case report

A 40-year-old Chinese man, resident in Italy for 12 years, came to our observation for a slowly-enlarging cutaneous nodular lesion on the dorsum of the left foot of one year's duration. Physical examination showed a 1.5 cm in diameter, blue-red colored, well circumscribed nodular cutaneous lesion (Fig. 1). The patient was otherwise in good health without any sign of immunodepression. On the suspicion of a vascular neoformation, the lesion was entirely excised and submitted for histological examination.

Microscopic examination showed a nodular lesion containing ample lacunae filled with a grainy amorphous material and extending to the deep dermis. The lacunae were surrounded by wide areas of dense acute and chronic granulomatous inflammation. The lesion was well circumscribed by a wall of fibrous tissue with deposition of newly formed collagen (Fig. 2).

An intricate mycelium embedded in amorphous material was detected in the center of the lacunae. The mycelial colonies were constituted by thin septate hyphae (diameter 2-6 µ) with voluminous roundish or polygonal chlamydospores at the extremities or in an intercalate fashion. The hyphae showed a constant tendency to conglobation and were cemented by an interstitial, uniform and adhesive, dark, abundant substance. This substance was intensely stained by periodic acid-Schiff (PAS), Ziehl-Neelsen, Gram and Silver-Methenamine stains and conferred a grainy aspect to the aggregations [7]. The surface of the colonies was usually surrounded by an inflammatory reaction rich in neutrophils, macrophages and containing several multinucleated giant cells [5, 8] (Fig. 3). Most of the grains were of a filamentous type [5, 6], composed of an uniform, adhesive cementing substance encompassing the hyphae, radially developing from the center to the periphery. The vesicular type grains [5, 6], formed by the cementing substance disposed at the periphery with vesicles terminating hyphae, were more rarely detected (Fig. 4). Highest magnification showed the presence of typical conidial bodies, recognized as phialophora type (chlamydospores) within the hyphae, some of which were bordered by eosinophilic Splendore-Hoeppli material [3, 9, 10] (Figs. 5 and 6). The overall features of the fungal structure were consistent with the typing of Madurella mycetomatis.

As requested by the patient, no systemic treatment followed the surgical removal of the lesion with no sign of recurrence at two year follow-up.

Discussion

Madura's foot is caused by the accidental inoculation of the pathogenic agent through the skin. Once the microrganism has reached the subcutaneous tissue it provokes a torpid inflammatory response with numerous abscesses, which reach the cutaneous surface through tortuous sinuses draining purulent material [4]. The infectious process may sometimes develop as an imposing proliferating mass. The infection may invade the deep tissues with joint damage [5] or penetration in internal organs causing the death of the patients [11]. Cases with central nervous system involvement have also been reported [12].

Madurella mycetomatis is commonly present in the ground and poor hygienic conditions, working without protective clothes and, above all, walking barefoot may all give rise to such a common infection in tropical regions [13-18].

Anyway our case seems to be imported. In fact, it is more likely that the patient was infected before his arrival in Italy, since he was coming from an endemic region for Madura's foot, Southern China, where barefoot working has been very common. Over 12 years time lag from probable inoculation to the clinical development of a lesion is not unusual and cases with up to twenty years have been described [2].

Our case is worth reporting because of the rarity of this disease in Europe. It also offers the opportunity to stress the need for clinical suspicion of this dermatosis, considering the increase in immigration towards our regions.

An early diagnosis is essential since the disease has a slow but relentless course with possible extension and damage of deep tissues and internal organs. Even if the clinical presentation is typical, histological and/or mycological examination are needed to differentiate mycotic and actinomycotic mycetomas with important therapeutical implications.

Treatment of mycotic mycetomas is often unsatisfactory. It is based on surgical excision since chemotherapeutic agents (ketoconazole, itraconazole) are expensive and often not effective [4, 5, 19-23]. A delayed diagnosis may require extensive excision which may not always be adequate.

Cases with unusual clinical presentation have been previously observed [24]. However, our case is peculiar for the pseudo-angiomatous aspect. As a matter of fact the absence of sinuses draining purulent grainy material, a vascular-like appearance, together with the total lack of clinical suspicion, were all factors contributing to the delayed diagnosis.

Article accepted on 2/9/00

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