Clinical and epidemiologic aspects of differential diagnostics of neoplastic, inflammatory and parasitic diseases localized in the maxillofacial region

S. I. Rapekta; Рапекта С. И.; A. A. Sletov; Слетов А. А.; N. V. Isaeva; Исаева Н. В.; G. I. Antakov; Антаков Г. И.; N. B. Liskov; Лисков Н. Б.; N. A. bykova; Быкова Н. А.

doi:10.17816/pmj424125-135

Clinical and epidemiologic aspects of differential diagnostics of neoplastic, inflammatory and parasitic diseases localized in the maxillofacial region

Authors: Rapekta S.I.¹, Sletov A.A.¹, Isaeva N.V.¹, Antakov G.I.¹, Liskov N.B.¹, bykova N.A.¹
Affiliations:
1. Ye.A. Vagner Perm State Medical University
Issue: Vol 42, No 4 (2025)
Pages: 125-135
Section: Methods of diagnostics and technologies
Submitted: 24.06.2025
Published: 11.09.2025
URL: https://permmedjournal.ru/PMJ/article/view/685670
DOI: https://doi.org/10.17816/pmj424125-135
ID: 685670

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Abstract

Objective. To study clinical and epidemiological features and develop an algorithm for differential diagnostics of neoplastic, inflammatory and parasitic maxillofacial diseases (exemplified by dirofilariasis).

Materials and methods. Retro- and prospective analysis of case histories of patients undergoing treatment for dirofilariasis in the Clinical Dental Hospital of Ye. A. Vagner PSMU since 2013.

Results. 35 cases of dirofilariasis were recorded in Perm Krai between 2013 and 2024, with 10 of them involving the soft tissues of the upper and middle facial thirds. These patients were hospitalized in the CDH of PSMU. Among the observed cases, the initial diagnosis correlated to the clinical one in only 50% of patients, in other cases it was established after surgical intervention. The criteria for differential diagnosis of dirofilariasis forms with neoplastic and inflammatory diseases were formulated in the course of the comparative analysis.

Conclusions. Dirofilariasis remains a rare and insufficiently studied pathology, including in the Perm region. In this regard, when patients complain of the development of tumor-like formations in the maxillofacial region, it is important to take the medical history thoroughly, focusing on the migration, sensations of moving and itching while moving. Take into account the seasonality, the presence of mosquitoes in the patient`s area of residence, pets, especially dogs. The need for multicenter research, which will raise the specialists` awareness in general and optimize the quality of medical care for patients with helminth infections, is obvious.

Keywords

Dirofilariasis, maxillofacial region, differential diagnosis, inflammatory diseases, neoplastic processes

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Introduction

Dirofilariasis is a parasitic disease transmitted by nematodes of the genus Dirofilaria after being bitten by blood-sucking insects (most often mosquitoes). Humans are usually facultative and dead-end hosts, but in some situations, they become the primary host, as confirmed by the recorded fact of prolonged microfilaremia [1]. The risk of infection is higher in people who are outdoors with exposed body parts, which explains the preferred localization of parasites in the maxillofacial region. In recent years, cases of infection have been recorded in cities, with the invasive stage occurring regardless of climate and season [2].

The incubation period depends on overall health, the growth rate of the parasite, and the external temperature (the process accelerates at temperatures above 14°C) [3; 4]. The first symptoms appear within a month to several years, which complicates diagnosis. The diagnosis is confirmed by the detection of an adult specimen [5]. A pathognomonic sign is migrating subcutaneous infiltrates with periodic local inflammation [6; 7].

Diagnosis of dirofilariasis is based on medical history, clinical presentation, and examination of extracted parasites. Additional methods are used instrumentally—ultrasound (US) and magnetic resonance imaging (MRI)—but they are not sufficiently informative, as they reveal a voluminous formation with clear contours and mobile or immobile inclusions [10]. The only effective treatment is surgical removal of the capsule containing the parasite [8–11].

Epidemiologists in Russia identify three endemic risk zones: low probability zone (number of days with temperatures above 14 °C – 60–90); moderate probability zone (favorable temperature period for the growth and development of dirofilariasis larvae – 90–105 days); stable probability zone (average daily temperature above 14 °C recorded for up to 150 days).

The Perm Krai region is located on the border between low and moderate risk zones, with at least three clinical cases detected annually. According to data from the Center for Hygiene and Epidemiology in the Perm Krai region, 35 cases of dirofilariasis were registered between 2013 and 2025.

The problems of diagnosis, treatment, and prevention of dirofilariasis are relevant due to the constant presence of mandatory sources of their spread—animals living in close proximity to humans [8]. A clear example of this fact is the results obtained for the period 2007–2016, when dogs kept at the canine center of the Main Directorate of the Ministry of Internal Affairs of Russia in the Perm Krai were repeatedly found to have dirofilariasis. Some departments have recorded a steady increase in carriers among service animals since 2010, peaking in 2013–2014, when microfilariae were detected in 16 (16.8%) of 95 samples received)1.

The risk of infection with dirofilariasis also exists in non-endemic regions. Insufficient awareness among medical professionals about the clinical and diagnostic characteristics of dirofilariasis, insufficient vigilance and awareness among the population about possible ways of infection and prevention of helminthiasis determined the aim and objectives of the study.

The aim of the study is to analyze the clinical and epidemiological features and develop an algorithm for the differential diagnosis of neoplastic, inflammatory, and parasitic diseases of the maxillofacial region.

Materials and Methods

Retrospective and prospective analysis of medical records of patients treated for dirofilariasis at the Clinical Dental Hospital of Ye.A. Vagner PSMU of the Russian Ministry of Health since 2013. Ten cases were registered with localization in the maxillofacial region: eight women and two men aged 15 to 72 years. Seven were residents of Perm, three were from the Perm Krai (two from Krasnokamsk and one from Lysva).

Statistical data show that 4 patients (40 %) were given a preliminary diagnosis of a neoplastic process upon hospitalization, one was diagnosed with chronic lymphadenitis (10 %), and 5 (50 %) were initially diagnosed with dirofilariasis.

The encapsulated form of dirofilariasis was detected in 8 patients (80 %), and the migrating form was detected in 2 (20 %) cases (Fig. 1).

Fig. 1. Clinical and epidemiological data on dirofilariasis of the maxillofacial region (Clinical Dental Hospital of Ye.A. Vagner PSMU)

A retrospective analysis of diagnostic errors revealed facts of differential diagnosis of dirofilariasis with tumor-like formations localized in the upper and middle thirds of the face.

The previously performed ultrasound and MRI scans provided by the patients were insufficiently informative, containing scant information about the volumetric formations localized in the subcutaneous adipose tissue of a particular area. The cytological examination data corresponded to the morphological picture of benign neoplasms, with no signs of atypia. When diagnosing neoplastic formations, specialists encountered difficulties, detecting tumor migration and periodic episodes of suppuration, which were relieved by taking antibacterial and anti-inflammatory drugs, as a result of which the “tumors” decreased to their original size or disappeared altogether. In clinical practice, there were anecdotal observations when one of the female patients reported the regular appearance and spontaneous disappearance of “lumps” accompanied by swelling of the surrounding tissues. These lumps had a distinctive ability to change their location, mainly occurring in the middle and upper third of the face. Their appearance was preceded by itching that moved around during the day, which could persist for a long time and was accompanied by pain.

As a result of intraoperative detection of a capsule with specific contents (Fig. 2, a, b), the main diagnosis was corrected to “dirofilariasis, encapsulated form”, performing all actions specified by epidemiological regulations.

Fig.2. Localization of the helminth in the maxillofacial region: a – helminth in the right temporal region; b – helminth capsule in the left cheek region; c – view of the removed capsule with a live helminth

Returning to diagnostic incidents, it is necessary to mention one more clinical observation. A 15-year-old girl was diagnosed with chronic lymphadenitis of the right submandibular region, accompanied by periodic pain for 4 months. These pains occurred spontaneously and disappeared after a course of antibiotic therapy. However, one month after the last exacerbation was relieved, the symptoms returned, and the patient sought medical advice. At the Clinical Dental Hospital of Ye.A. Vagner PSMU, an excisional biopsy was performed, which resulted in the discovery and removal of a capsule containing a live helminth 10 cm long (Fig. 2, c).

When analyzing clinical experience, it is important to emphasize the importance of an approach that seems obvious but is often ignored: carefully collecting the patient's medical history and complaints, paying particular attention to specific symptoms that are often found in helminth infections localized in the tissues of the maxillofacial region.

Between 2017 and 2025, five patients were diagnosed with maxillofacial dirofilariasis at the time of hospitalization: three cases involved the encapsulated form of helminthiasis, and two involved the migratory form. According to the researchers, the migrating form always precedes the encapsulated form. In situations where helminth migration is not active, it does not even cause discomfort to the patient, which smooths out clinical manifestations, preventing early treatment, the need for which arises during the period of inflammatory reactions of the encapsulated form. It is at this point that patients forget fundamentally important anamnestic data, focusing instead on recent events that are not only uninformative but also lead to diagnostic errors.

When analyzing the effectiveness of surgical treatment of patients with migratory dirofilariasis, a number of objective technical difficulties have been identified: absence of a capsule; hypermobility of the helminth, allowing it to quickly change its location in soft tissues. These factors make the helminth difficult to detect during surgery.

An interesting observation has been recorded: a 27-year-old female patient was urgently hospitalized with psychoemotional agitation against the background of painful infiltrate migration between different areas of the face and head. For two months, the patient noted unusual sensations in the form of subcutaneous movement and displacement of the infiltrate from the right paraorbital region through the root of the nose to the left paraorbital region, then to the corner of the mouth and further to the neck region. Then, turning around, it migrated to the temporal region, then to the occipital region and the chin area, completing the migration cycle in the right cheekbone region. The patient visited the reception department of the Clinical Dental Hospital of the Ye. A. Vagner PSMU twice, but due to the lack of convincing clinical data for helminthiasis (it was not possible to determine the helminth either visually or by palpation), no surgical intervention was performed. In the photos presented (Fig. 3, a), taken on the eve of the visit, signs of subcutaneous localization of the parasite are visualized in the left suborbital region.

Fig. 3. Visualization of the helminth in the maxillofacial region: a ‒ outline of the parasite in the suborbital region on the left along the ciliary margin of the lower eyelid; b – visualization of the area of skin hyperemia and a barely palpable cord in the right cheekbone area; c – moment of removal of the helminth from the subcutaneous fatty tissue above the right cheekbone

The helminth was successfully removed only after repeated treatment, following visualization and palpation to determine its boundaries in the tissues above the right zygomatic bone. Probably due to the presence of a dense base, which was the body of the zygomatic bone, with a small thickness of tissue above it, we were able to determine a barely palpable cord, which is shown in the photo (Fig. 3, b).

In three cases, patients were diagnosed with encapsulated form of dirofilariasis upon hospitalization, complaining of a previously migrating formation in various anatomical areas, indicating a previous migrating form of dirofilariasis. In only one case out of all cases did the patient not notice any movement of the helminth.

Based on the results of the ultrasound examination (Fig. 4, a), the following picture was observed: a spherical anechoic formation of heterogeneous structure with a pronounced echogenic capsule. Mobile structures are identified in the cavity, tubular in shape, with a diameter of up to 0.8 mm and clear contours, which largely corresponds to the description of a live helminth in a capsule. Based on the MRI image, a conclusion is made about the presence of an encapsulated cavity formation in the soft tissues (Fig. 4, b).

Fig. 4. Results of additional (imaging) examination methods: a – ultrasound image of encapsulated dirofilariasis; b – MRI image of encapsulated dirofilariasis with capsule localization in the soft tissues of the right cheek area

In all of the above observations, cytological examination revealed blood cells, cells with foamy cytoplasm, and small homogeneous nuclei.

Based on the medical history and the results presented above, a diagnosis of “dirofilariasis, encapsulated form” was made. Surgical treatment was performed to extract the parasite and remove its capsule (Fig. 5, a–c).

Fig. 5. Intraoperative photographs: a, b – removal of the helminth; c – removed helminth

All facts of the disease have been confirmed morphologically. Pathohistological studies were conducted in the laboratory of the Clinical Dental Hospital of Ye. A. Vagner PSMU of the Ministry of Health of Russia. All patients under observation with a diagnosis of “dirofilariasis, encapsulated form” underwent pathohistological examination of material taken during surgical interventions. Microscopic description: the capsule wall is represented by mature granulation connective tissue (1) with blood vessels (2) and moderate infiltration of neutrophilic leukocytes (3) (Fig. 6, a, b).

Fig. 6. Microscopic image of a helminth capsule (a, b)

Parasitological studies of helminths were conducted in the laboratories of the Perm Krai Center for Hygiene and Epidemiology. Each study identified specimens of the genus Dirofilaria ranging from 10 to 18 cm in length, with 7 observations of immature females and 3 observations of mature females (Fig. 7, a, b).

Fig. 7. Visualization of helminths during parasitological examination: a – Dirofilaria, showing the head end; b – Dirofilaria, head and tail ends

Results and Discussion

35 cases of dirofilariasis were recorded in the Perm Krai between 2013 and 2024. Ten of these patients, with the disease localized in the soft tissues of the upper and middle third of the face, were hospitalized at the Clinical Dental Hospital of the Ye.A. Vagner PSMU. Of those under observation, only 50 % of patients had a preliminary diagnosis that corresponded to the clinical diagnosis; in the remaining cases, the diagnosis was made after surgical intervention. Given the identified frequency of diagnostic errors, this study focuses on analyzing anamnestic data and macromorphological characteristics of tumor-like formations detected in soft tissues, monitoring their size and location. The similarities and differences between dirofilariasis and tumorous, chronic inflammatory diseases of the maxillofacial region (Fig. 8) are proposed for public discussion).

Fig. 8. Differential diagnosis of forms of dirofilariasis with neoplastic and inflammatory diseases

A comparative analysis of the results of additional diagnostic methods (MRI and ultrasound) has shown that these methods are not sufficiently informative, which is probably due to the low radiopacity of the morphological structures of the parasite. The cytological results obtained also do not contain objective data. The most reliable symptoms include: migration of tumor-like formations, the intensity of which is determined by many factors related to the general condition of the body and climatic conditions of the environment; progressive itching accompanied by a feeling of movement of an object under the skin; changes in the size of the formation, up to its complete but temporary disappearance against the background of taking antibacterial drugs; seasonality of the disease.

The presented observation results fully correspond to the clinical and morphological classification of forms of dirofilariasis, encapsulated and migratory, characterized by the appearance of dense painful or painless, itchy, tumor-like infiltrates. Unlike the encapsulated form, the migratory form is characterized by the movement of the infiltrate and its disappearance from its previous location (see Fig. 8). In this regard, the migratory form must be differentiated from inflammatory processes, and the encapsulated form from neoplastic processes.

Conclusions

Heartworm disease remains a rare and poorly understood pathology, including in the Perm Krai region. Therefore, when treating patients with complaints of tumor-like formations in the maxillofacial region, it is important to carefully collect their medical history, focusing on the migration of the formation, sensations of movement and itching along its path. Seasonality should be taken into account, as well as the presence of mosquitoes in the patient's habitat and domestic pets, especially dogs. The use of the developed algorithm for the differential diagnosis of neoplastic, inflammatory, and parasitic diseases of the maxillofacial region (using the example of dirofilariasis) contributes to improving the quality of medical care, and this study will increase the awareness of specialists in general.

1 A.V. Skryabina. Dirofilariasis in service dogs in the Perm Krai (prevalence, serological monitoring, cariopathic effect of Dirofilaria immitis antigens and antiparasitic drugs): dissertation ... Candidate of Biological Sciences. Moscow, 2017.