Cutaneous nocardiosis with discharging sinus clinically mimicking tuberculosis diagnosed by cytology

Abstract

Nocardiosis is primarily a pulmonary infection commonly seen in immunocompromised individuals. However, lymphocutaneous nocardiosis is observed in immunocompetent individuals often after trauma. The clinical and cytomorphological features of lymphocutaneous nocardiosis closely mimic the most common infections in India such as tuberculosis and mycetoma (very common cutaneous infection with discharging sinus). As it is crucial to differentiate nocardiosis from tuberculosis, to avoid unnecessary antitubercular treatment, special stains like modified Ziehl–Neelsen stain and Gram stain can be employed to differentiate the morphology of Nocardia from tuberculosis. Fine‐needle cytology from these cutaneous lesions helps in yielding adequate material for rapid and accurate diagnosis of immediate specific antibiotic treatment. We report a rare case that presented with clinical diagnosis of tuberculosis but turned out to be nocardiosis on cytomorphology with simple and most feasible fine‐needle aspiration method of tissue diagnosis and scrape cytology.

Cyto‐morphological and clinical approach to infections presenting with discharging sinuses mimicking malignancy

“…Pulmonary, disseminated, and cutaneous forms are the various presentations of nocardiosis. The most common organism isolated in the cutaneous form is Nocardia braziliensis 7 . Clinically patients present with cellulitis of arm or foot, with or without accompanied regional lymphadenopathy.…”

Primary Cutaneous Nocardiosis: A Rare Presentation of Nocardiosis

“…Primary cutaneous disease is often followed by traumatic implantation of the nocardia bacterium after splinter injury [5,6,12]. The secondary cutaneous disease can occur after the dissemination of the pulmonary disease leading to secondary focus created in the skin.…”

“…Our case is unique because cutaneous nocardiosis is a rare manifestation and has a tendency to be misdiagnosed because it can mimic other skin diseases such as pyoderma, Leishmaniasis, tuberculosis (when it presents as a lympho-cutaneous disease) and cellulitis (such as in this case) [5-6]. This case is also distinctive due to the fact that cutaneous nocardiosis is a rare disease itself and should be suspected especially in cases of traumatic injury or splinter injury, as was seen in the case presented.…”

“…Gram staining shows thin filaments of gram-positive aerobes. Ziehl-Neelsen stain with 1% sulfuric acid is used instead of 20% for the identification of Nocardia species, however, it is less sensitive [5-6]. Nocardia grows on most media, culture takes 5-7 days to grow.…”

Other Bacterial Infections of the Skin

“…Actinomycosis, tuberculosis, atypical mycobacterial infections, histoplasmosis, sporotrichosis, and coccidioidomycosis (pathogens of lymphocutaneous syndromes) are to be distinguished (Gudivada et al 2019).…”