CASE 18823 Published on 17.01.2025

Unilateral axillary lymphadenopathy, a rare presentation of toxoplasmosis

Section

Breast imaging

Case Type

Clinical Case

Authors

Rita Cartucho 1, Raquel Dias 2, José Cabeçadas 2

1 Hospital Professor Doutor Fernando Fonseca, Unidade Local de Saúde (ULS) Amadora / Sintra, Amadora, Portugal

2 Instituto Português de Oncologia de Lisboa Francisco Gentil, Lisbon, Portugal

Patient

43 years, female

Categories
Area of Interest Breast ; Imaging Technique Mammography, Ultrasound
Clinical History

A 43-year-old woman presented with complaints of a lump in the left axilla. She had no clinically significant background. History of breast cancer in her family was positive for her mother, at 49 years old. Physical examination revealed axillary adenomegalies of elastic consistency, mobile and slightly painful to touch.

Imaging Findings

We started the evaluation with bilateral mammography, and breast and axillary ultrasound. Mammographic projections revealed dense breast tissue (ACR category C) with no concerning features, such as focal asymmetries, nodular densities or grouped microcalcifications (Figure 1).

Complementary ultrasound evaluation did not reveal suspicious breast lesions. However, ultrasound evaluation of the left axilla revealed several lymphadenopathies with cortical thickness >3 mm, reduction of the fatty hilum, round shape and/or lobulated cortex and hypoechoic texture (Figures 2a and 2b). Lymph nodes on the right axilla were considered normal (not shown). A left lymph node core biopsy was performed on the lymph node with the highest cortical thickening (Figures 2c and 2d).

As the mammographic study was limited by dense breast tissue, we directly performed a contrast-enhanced mammogram (CEM) to search for occult breast neoplasia. No hypervascular lesions were noted (Figure 3). Histopathologic examination suggested the diagnosis of toxoplasmosis (Figures 4a and 4b), which was further confirmed by serologic tests.

Discussion

Toxoplasma gondii, an intracellular protozoan parasite with worldwide distribution, is responsible for the infectious disease named toxoplasmosis. Transmission from animals to humans occurs when infectious oocysts present in cat faeces contaminate raw meat/water. When Toxoplasma gondii oocysts invade the intestinal epithelium, they disseminate and encyst in any nucleated cell. The combination of oocysts proliferation with the host’s immune response may cause clinical manifestations. Even so, most immunocompetent hosts with primary infection are asymptomatic (8090% of cases). When symptoms do occur, they typically are self-limited and develop 5 to 23 days after exposure to the parasite. Isolated cervical or occipital lymphadenopathy is the most common symptom, followed by constitutional symptoms [1,2]. Axillary lymphadenopathy is a rare form of presentation [35], resulting in a rare presumed diagnosis without proceeding to microbiopsy or cytology. After the anatomopathological suggestion of toxoplasmic lymphadenopathy, the diagnosis must be confirmed by serological tests [4,6].

The most common cause of unilateral axillary adenopathy is upper limb infection/injury, as systemic illnesssuch as autoimmune/granulomatous diseases, metastases or lymphoproliferative diseasecommonly presents with more generalised involvement [5,7]. Another possible cause in female patients is breast malignancy, which further obligates imaging workup with at least mammography and breast ultrasound [8]. This is particularly relevant when features of malignancy are present on physical examination (firm, hard, tender, fixed or matted nodes).

Sonographic assessment of lymph nodes implies a systematic evaluation of different morphological parameterssuch as shape and cortical morphologic features, and hilum/cortex vascularisation on Doppler ultrasound. Focal hypoechoic cortical lobulation or round shape with an absence of the fatty hilum (hypoechoic node) are worrisome features and mandate further cytological or histological studies. This is explained as metastatic deposits are arrested by immune cells in the periphery of a node, causing focal enlargement of the cortex. As a focal metastatic deposit enlarges, replacement of the fatty hilum is established, leading to the commonly described round hypoechoic node. A lymph node with an imperceptible cortex, a thin 3-mm or less cortex, or a diffuse symmetric cortical thickening of more than 3 mm, is considered benign. Generalised lobulated cortical thickening is regarded as a likely benign node and does not demand pathological characterisation. A peripheral nonhilar blood flow is considered a suspicious feature of malignancy [810].

In our case, mammography, breast ultrasound and even CEM were innocent. Although rare, the possibility of facing a malignant entity with lymphatic unilateral presentationoccult breast tumour, lymphoma or metastasesforced the biopsy. Even so, we believe that if a proper clinical history had been collected in the first placeregarding recent contact with cats, alimentary habits, history of systemic symptoms, we could have reassured the patient that we were probably facing a benign pathology.

In conclusion, many different benign and malignant pathologies can be responsible for axillary adenopathies. Collecting clinical data can help prevent unnecessary imaging workup and/or biopsy.

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Recent infection/trauma in the ipsilateral upper limb, breast or upper thoracic tissue
Granulomatous disease / systemic infection
Primary breast neoplasia with axillary lymphatic involvement
Axillary lymphatic metastases due to a neoplastic source
Toxoplasmic lymphadenopathy
Lymphoproliferative disease
Final Diagnosis
Toxoplasmic lymphadenopathy
Case information
URL: https://www.eurorad.org/case/18823
DOI: 10.35100/eurorad/case.18823
ISSN: 1563-4086
License