Tropical Dermatological Care at the Bundeswehr Hospital Hamburg in Collaboration with the Bernhard Nocht Institute for Tropical ­Medicine: Historical Development, Clinical Case Studies, and Future Challenges

Lennart Lemmermann^a, Aleksandr Sumenko^a, Marcellus Fischer^a, Elmar Elsner^a

^a Department of Dermatology, Venereology, and Allergology, Bundeswehr Hospital Hamburg

Summary

Tropical dermatology is a vital component of infectious and dermatological care, particularly in light of increasing global mobility and projected worldwide military deployments. At the Bundeswehr Hospital Hamburg, care is provided in close cooperation with the Bernhard Nocht Institute for Tropical Medicine, which has a long-standing tradition in research, diagnosis, and treatment of tropical diseases. Selected clinical case studies from the tropical dermatology department are used to present both common and rare diseases, placing them in their historical and current context.

In addition to deep mycoses such as chromoblastomycosis and eumycetoma, which pose challenges due to their chronic course and often prolonged therapy, cutaneous leishmaniasis is highlighted as a more common parasitic disease with particular relevance in military context. The case studies illustrate the diagnostic and therapeutic challenges, particularly against the backdrop of limited clinical experience with rare entities in non-endemic regions. Simultaneously, a significant portion of tropical infectious diseases exhibit early skin manifestations, which can serve as crucial clinical indicators. Overall, tropical dermatology is gaining importance in the face of global mobility, migration, and changing geopolitical deployment scenarios. Close interdisciplinary collaboration and the expansion of preventive, diagnostic, and therapeutic competencies are essential to ensure adequate care for affected patients.

Keywords: Tropical Dermatology; Leishmaniasis; Deep Mycoses; Deployment Medicine; Rickettsioses; Infectious Dermatology

Introduction

The Bundeswehr Hospital (BwKrhs) Hamburg and the Bernhard Nocht Institute for Tropical Medicine boast a rich history. As the Port of Hamburg became a growing hub for colonial goods, there was an increasing confrontation with novel diseases from distant regions. To address these challenges, Bernhard Nocht, who was a naval physician at the time and is now the institute’s namesake, was appointed the first port physician at the end of the 19th century. The actual work of the “Institute for Maritime and Tropical Diseases” began on 1^st October 1900. A central task of the institute was quickly defined: future epidemics, such as the previously experienced cholera outbreak, should be effectively prevented through early detection and prevention [8][13].

Today, the institute is among the world’s leading institutions in tropical medicine and has significantly contributed to the research, diagnosis, and treatment of tropical infectious diseases since its founding. A focus on tropical dermatology was established early on, which continues to reflect in the close cooperation within the tropical dermatology clinic of the Department of Dermatology, Venereology, and Allergology at the BwKrhs Hamburg, forming an important part of specialized medical care. Against the backdrop of increasing globalization, international travel, migration, and military deployments abroad, the spectrum of tropical dermatological diseases has expanded considerably, with skin manifestations still playing a central role as diagnostic lead symptoms [5].

The aim of this article is to illustrate the broad spectrum of tropical dermatological diseases using selected case studies from our clinic, to contextualize their historical development, and to discuss future challenges in both military and civilian contexts.

Deep Mycoses: Rare but Clinically Relevant ­Entities

Chromoblastomycosis

A historically significant example of diseases first described by German military doctors in the context of tropical medical observations is chromoblastomycosis. It was first described in 1914 by the German ship’s doctor Max Rudolph, who initially called it “Brazilian Figueira” [14]. It remains a rare but clinically relevant disease to this day. The close connection between dermatological expertise and tropical medical research has thus evolved historically and continues to shape the care provided at the Hamburg location.

Infection Pathway

Chromoblastomycosis typically arises from traumatic inoculation with Phialophora verrucosa, a pathogen from the group of black fungi (family Dematiaceae). These fungi are found in soil and decaying plant material, particularly in tropical and subtropical regions of South America. The rural population is primarily affected in the context of agricultural activities, where small skin injuries and subsequent inoculation of the pathogen into subcutaneous fat tissue may occur. However, chromoblastomycosis can also occur as a so-called “vacation dermatosis” in travelers who spend time in endemic regions [10][12].

Clinical Presentation and Diagnosis

Following inoculation, a papular skin lesion typically develops at the affected site. This lesion usually progresses slowly over months to years with ulcerations and verrucous or psoriasiform changes. In later, untreated stages, there may be significant progression with crusty, hyperpigmented, map-like, and sometimes massively verrucous skin changes [4]. Diagnosis is confirmed clinically and through histological and cultural pathogen detection [14].

Therapy

The management of chromoblastomycosis remains challenging and frequently requires prolonged therapeutic intervention. In early-stage disease, complete surgical excision may be considered for small, localized lesions; subsequent antifungal therapy is recommended. In advanced or inoperable cases, systemic antifungal treatment is indicated. First-line agents include oral antifungals such as itraconazole (200–400 mg/day) or terbinafine (250–500 mg/day). In severe or treatment-refractory cases, combination therapies or alternative substances like amphotericin B may be used, although its application is limited due to potential side effects. The treatment duration is long, often lasting at least six to twelve months, sometimes significantly longer. It is important to note that the disease shows a slow clinical response and recurrences are not uncommon, necessitating consistent and long-term treatment [9].

Eumycetoma

Pathogen and Infection Pathway

Another example is eumycetoma, also a deep mycosis and chronic granulomatous infection of the skin and subcutis [17]. Infections with Madurella mycetomatis, the most common pathogen of eumycetoma, occur predominantly in arid climates of East Africa (the so-called “Mycetoma Belt”) as well as in India. Transmission typically occurs through traumatic inoculation, such as puncture wounds from barefoot walking. Consequently, men working in agriculture in endemic regions are particularly affected. Additionally, the World Health Organization classifies eumycetoma as an NTD (Neglected Tropical Disease) [18].

Clinical Presentation and Diagnosis

Clinically, eumycetoma presents as a chronic, progressive granulomatous inflammation, often accompanied by purulent secretions and fistula formation. Characteristic is the slow progression with increasing tissue destruction, where in advanced stages even osseous structures may be affected. Due to the preferred localisation in the foot area in over 65 % of cases, eumycetoma can lead to significant functional impairments, deformities and amputations, when untreated [17].

Therapy

Therapy is challenging due to deep tissue involvement and often delayed diagnosis. Surgical treatment alone is usually insufficient and should always be supplemented by long-term systemic antifungal therapy. Itraconazole is the first-choice medication, especially in cases of proven resistance to terbinafine, and is used in dosages of 200–400 mg/day over several months up to 1.5 years. Alternative treatment options include azoles like voriconazole or posaconazole [1].

Eumycetoma Case Study

A 45-year-old patient from Sudan presented to the tropical dermatology clinic with a recurrence of eumycetoma on the forefoot. Three years earlier, a primary excision of a nodular skin lesion at the same site had been performed on an outpatient basis, but without accompanying antifungal therapy. The histopathological finding was consistent with eumycetoma. Upon re-evaluation, an approximately 2 × 1 cm area was observed on the medial side of the proximal phalanx of the right big toe (D I), extending into the interdigital space I – II, with individually grouped, ulcerated, exophytic nodules covered with serocrusts (Figure 1).

Fig. 1: Initial Findings (Eumycetoma): Individually grouped, ulcerated, exophytic nodules with overlying serocrusts in an area measuring approximately 2 x 1 cm (Image rights: Department of Dermatology, BwKrhs Hamburg)

The diagnosis was achieved by histopathological examination, microbiological culture, and molecular genetic testing, which identified Madurella mycetomatis as the etiologic pathogen. Histopathologically, a pronounced inflammatory infiltrate with fibroses and encapsulated granuloma-like, dense, granulocytic inflammatory reactions were observed. Larger granules with hyphae in a brownish matrix were found centrally. Fungal elements were detected in PAS staining. The excision was not performed in healthy tissue at the base (Figures 2 and 3). In the microbiological culture, dark colonies grew, consistent with Madurella mycetomatis (Figure 4).

Fig. 2: Eumycetoma: More severe inflammatory infiltrate and fibroses with encapsulated granuloma-like dense, granulocytic inflammatory infiltrates (Image rights: Dermatohistopathology Dr. Günzl, Hamburg)

Fig. 3: Eumycetoma: Large granules with hyphae in a brownish matrix (Image rights: Dermatohistopathology Dr. Günzl, Hamburg)

Fig. 4: Eumycetoma: Slow growth of dark colonies consistent with Madurella mycetomatis (Image rights: Department of Dermatology, BwKrhs Hamburg)

Molecular genetic testing using polymerase chain reaction (PCR) and sequencing confirmed the presence of the pathogen. Resistance testing showed resistance to terbinafine (MIC > 8) and sensitivity to itraconazole (MIC 0.006). The therapy consisted of a combination of surgical cleaning and long-term systemic antifungal therapy with itraconazole 200 mg daily for twelve months. Under this therapy, complete clinical healing was achieved, and after 14 months of follow-up, the skin lesion showed complete regression with formation of a non-irritated scar.

Deep Mycoses: Diagnostic and Therapeutic Challenges

The presented examples highlight the diagnostic and especially therapeutic challenges associated with deep mycoses. The case study showed that initial treatment with surgery alone, without adequate antifungal therapy, can lead to an increased risk of recurrence. It was only through the combination of surgical cleaning and consistent, long-term systemic therapy that complete healing was achieved. This underscores the critical importance of interdisciplinary, specialized tropical dermatological management in the treatment of deep mycoses.

Parasitic Diseases

Cutaneous Leishmaniasis

Unlike rare deep mycoses, parasitic infections constitute a significantly more frequent portion of tropical dermatological diseases. Cutaneous leishmaniasis is an example with particular significance in the military context.

Infection Pathway

The vector-borne disease is caused by protozoa of the genus Leishmania spp.and transmitted through the bite of sand flies of the genera Phlebotomus and Lutzomyia. Like eumycetoma, it is classified as an NTD and poses not only a significant health issue but also a considerable socioeconomic burden for affected populations. The disease is endemic in numerous regions, particularly the Mediterranean, the Middle East, as well as parts of Africa and Latin America. Annually, up to one million new cases occur. In Europe, leishmaniasis primarily occurs in returning travelers and refugees from endemic areas [6]. Additionally, isolated cases have been reported following vacations, for example, in Mallorca [15].

Clinical Presentation and Diagnosis

Depending on the Leishmania species, three clinical manifestation forms are distinguished: cutaneous, mucocutaneous, and visceral leishmaniasis. Differentiating these forms and the respective species is crucial for choosing the appropriate therapy. Additionally, pathogens of the “Old World,” primarily found in the Mediterranean, the Middle East, India, and Africa, often present with self-limiting, yet ulcerative skin lesions (e.g., L. major, L. infantum, L. tropica), while “New World” pathogens, prevalent in Central and South America (e.g., L. amazonensis, L. mexicana, L. (Viannia) naiffi, L. braziliensis, L. guyanensis), are more frequently associated with severe, sometimes destructive courses and often present in a mucocutaneous form [6].

Clinically, cutaneous leishmaniasis typically manifests initially as a papular lesion, which can ulcerate over time, often featuring central necrosis and progressing to a chronic, therapy-resistant wound. Especially, immunosuppressed patients tend to develop atypical, disseminated or particularly severe lesions, sometimes with a long latency between exposure and the onset of clinical manifestation [3][6].

Diagnosis is complicated by limited clinical experience in non-endemic regions and low pathogen density in tissue. Additionally, a significant temporal latency between staying in an endemic region and the onset of symptoms can exist, making the connection not always immediately apparent. Diagnosis is initially based on history and clinical findings. Confirmation is provided by direct microscopic pathogen detection and molecular genetic methods (PCR and sequencing), which are considered the diagnostic gold standard. Additionally, cultural cultivation and serological tests are employed [3].

Therapy

In cutaneous leishmaniasis, spontaneous healing with scarring may occur even without further treatment. If this does not happen, therapy can be complex and multifaceted. As a general rule, the species should be identified as accurately as possible before beginning treatment in order to ensure targeted therapy. Local therapeutic methods include intralesional application of meglumine antimonate (Glucantime) and topical application of paromomycin in combination with methylbenzethonium chloride, which is currently unavailable in Germany. Cryotherapy may show synergistic effects in combination with intralesional antimony preparations. Furthermore, thermotherapy and photodynamic therapy (PDT) have been used successfully [2][6].

Systemic therapy options include miltefosine and amphotericin B, with the latter especially used in immunosuppressed patients [3][6]. Parenterally administered antimony preparations remain an established treatment option in many endemic areas but are limited due to the frequent occurrence of sometimes severe side effects, particularly cardiotoxic and pancreatotoxic effects [3][6][16].

Cutaneous Leishmaniasis Case Study

A case from the tropical dermatology clinic involves a 42-year-old patient with complex cutaneous leishmaniasis undergoing immunosuppressive therapy with fingolimod. Anamnestically, a progressive, partially exudative ulceration in the sacral area had existed since May 2022. The patient previously had spent several weeks in southern Spain (Alicante region). Additionally, the patient had a history of sinus pilonidalis, leading to the lesion initially being misinterpreted as a recurrence. Clinically, at presentation, there was a large, approximately 20 × 10 cm and up to 3 cm deep ulcer in the sacral area with a nodular border and fibrin-coated wound base (Figure 5). Involvement of deeper structures and visceral manifestation were excluded through imaging. Further diagnostics through histology and molecular genetic pathogen detection confirmed cutaneous leishmaniasis caused by Leishmania infantum.

Fig. 5: Cutaneous Leishmaniasis (Initial Findings): An approximately 20 × 10 cm and up to 3 cm deep ulcer in the sacral area with a nodular border and fibrin-coated wound base (Image rights: Department of Dermatology, BwKrhs Hamburg)

Initial systemic treatment with liposomal amphotericin B resulted in a temporary clinical response; however, despite this initial improvement, disease progression recurred in the setting of ongoing immunosuppression with fingolimod. Due to the therapy-refractory course, a combined therapy was initiated, consisting of systemic treatment with miltefosine and repeated intralesional injections of meglumine antimonate. Additionally, a structured, stage-appropriate wound therapy was performed with antiseptic cleaning, the application of modern wound dressings, and close follow-up. Under this multimodal therapy, there was continuous improvement with increasing granulation and epithelialization. Ultimately, about a year after the initial manifestation, complete healing with scar formation was achieved (Figure 6).

Fig. 6: Cutaneous Leishmaniasis (Final Findings): Healing with scar formation (Image rights Department of Dermatology, BwKrHs Hamburg)

This case illustrates the complexity of treating cutaneous leishmaniasis as a cause of chronic ulceration. Only through the optimal interplay of causal therapy and wound treatment can a satisfactory treatment outcome be quickly achieved, necessitating close collaboration of tropical medical, dermatological, and wound therapeutic expertise.

Discussion

History has repeatedly shown that infectious diseases spread particularly easily under wartime conditions. A historical example is endemic typhus, transmitted by body lice (Pediculus humanus corporis), which was of great significance during World War I and II. Significant contributions to its research were made by staff at the Bernhard Nocht Institute for Tropical Medicine, including Stanislaus von Prowazek and Henrique da Rocha Lima. The pathogen, Rickettsia prowazekii, was ultimately named after von Prowazek, who died in the course of his research. Although this disease plays little role today, other rickettsioses are increasingly diagnosed in travelers returning from regions such as sub-Saharan Africa. They are often characterized by skin manifestations like an eschar (Tache noire), which serves as a guiding clinical finding and underscores the role of the skin as a diagnostic window [7][11]. In light of current geopolitical developments, such as the war in Ukraine, it is not impossible that more cases may occur in Europe again.

The presented case studies illustrate the range of tropical dermatological diseases diagnosed and treated at the BwKrhs Hamburg in cooperation with the Bernhard Nocht Institute. The combination of clinical expertise and specialized diagnostics enables adequate care. A central aspect is the structured collaboration between clinical facilities and tropical medical specialty centers.

In tropical medicine, dermatology plays a special role, as a significant proportion of tropical diseases exhibit skin manifestations that often serve as the first clinical indication of the underlying disease. The skin is thus not only a target organ but also an important diagnostic window, requiring high clinical attention and specific expertise.

Tropical Dermatology in Military and Civilian Contexts

Looking to the future, an increase in tropical dermatological issues is expected. Besides globalization, military deployment scenarios also play a crucial role. While there has been an increased focus on Eastern European regions over the past four years, there is simultaneously an observed increase in political instability in parts of the Middle East. Both regions are associated with specific infectious risks and require appropriate medical preparation and expertise.

In the military context, preventive measures, in addition to diagnostics and therapy, play a particularly important role. These include exposure prophylaxis through protective clothing and repellents, as well as early medical clarification of symptoms after staying in endemic areas. As illustrated, cutaneous leishmaniasis has gained increased importance in military deployments in endemic regions, particularly in the Middle East. Deployments like those in Afghanistan have led to increased exposure in the past. The disease poses not only a medical but also a deployment-relevant problem, as it can lead to extended downtimes. It remains relevant against the backdrop of ongoing geopolitical tensions and potential military engagements in endemic regions.

In the civilian context, due to global mobility and migration, an increasing number of imported cases are expected in non-endemic countries like Germany, requiring heightened clinical attention. Consequently, healthcare systems must continuously adapt their diagnostic and therapeutic capacities, accompanied by targeted education and specialized training in tropical dermatology.

Conclusion

In summary, tropical dermatology is an essential component of dermatological and infectious disease care. The combination of early diagnosis, interdisciplinary collaboration, and specialized expertise, as implemented at the BwKrHs Hamburg in cooperation with the Bernhard Nocht Institute, is crucial to effectively address these challenges.

Key Messages

• Tropical dermatology is essential for diagnosing and treating infectious diseases in the context of global mobility and military deployment.
• Many tropical infections exhibit skin manifestations as early diagnostic lead symptoms.
• Deep mycoses are rare but present diagnostically and therapeutically relevant challenges.
• Cutaneous leishmaniasis is a common, clinically variable, and deployment-relevant tropical infection.
• New deployment scenarios can increase the relevance of vector-borne diseases.

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Manuscript Data

Citation

Lemmermann L, Sumenko A, Fischer M, Elsner E. Tropical Dermatological Care at the Bundeswehr Hospital Hamburg in Collaboration with the Bernhard Nocht Institute for Tropical Medicine: Historical Development, Clinical Case Studies, and Future Challenges. WMM 2026;70(9E):4.

DOI: https://doi.org/10.48701/opus4-968

For the Authors

Medical Officer Lennart Lemmermann

Department of Dermatology, Venereology, and Allergology

Bundeswehr Hospital Hamburg

Lesserstraße 180, 22049 Wandsbek

E-Mail: lennartlemmermann@bundeswehr.org