A 68-year-old Chinese man presented with enlarging erythematous plaques with erosions and swelling on his right forearm for 6 months. His lesions were accompanied by itching, without any history of fever or pain. After discontinuous antibiotic therapies, the condition slightly improved. However, almost 2 months ago, the initial lesions got worst, with the development of similar lesions around the cubital fossa presented with ulceration and exudates. He had a history of well-controlled diabetes for 4 years. Dermatological examination revealed 8 cm × 6 cm and 6 cm × 4 cm erythematous plaques with erosions, edema, and brown crusts on the right arm [Figure 1].
Figure 1
Right forearm image of the patient. Image showing the erythematous plaques with erosions, edema, and brown crusts.
Right forearm image of the patient. Image showing the erythematous plaques with erosions, edema, and brown crusts.Histopathological examination of the biopsy specimen revealed massive infiltration of inflammatory cells in the dermis and scattered epithelioid granuloma [Figure 2]. Special staining for PAS, chloramine silver, and acid-fast staining were insignificant. In the skin biopsy specimen culture, dry, chalky white colonies were found in rabbit blood agar, and Gram's stain smear showed gram-positive beaded branching filaments [Figure 3].
Figure 2
Histopathological image. Microscopic image with massive infiltration of inflammatory cells and scattered epithelioid granuloma in the dermis (HE × 40).
Histopathological image. Microscopic image with massive infiltration of inflammatory cells and scattered epithelioid granuloma in the dermis (HE × 40).Gram stain smear showed Gram-positive beaded branching filaments (original magnification × 1000).
What is Your Diagnosis?
DiagnosisPrimary cutaneous nocardiosis
Discussion
Primary cutaneous nocardiosis is an unusual disease of gram-positive Nocardiaceae infections caused by Nocardia species (family Actinomycetaceae). Nocardiosis is usually seen in immunocompromised individuals such as those with autoimmune disease, malignancy, diabetes, or AIDS. Therefore, it is generally considered an opportunistic infection. Its clinical variability includes lymphocutaneous syndrome,[1] superficial skin infection[2] (pustule, pyoderma, abscess, ulcer, granuloma, or cellulitis), chronic conditions of hyperkeratotic plaques, tumor-like masses, and mycetoma[3] along with systemic nocardiosis cutaneous involvement. In some instances, the infection may also be subclinical and resolve spontaneously.Diagnosis of primary cutaneous nocardiosis can be confirmed through culture and molecular sequencing of the skin biopsy specimen. As the colony of culture grows very slowly, it may lead to false-negative culture, resulting in misdiagnosis.Primary cutaneous nocardiosis should be differentiated from lymphatic spread sporotrichosis, nontuberculous mycobacterial infection, and skin squamous cell carcinoma with infection. A typical lymphatic sporotrichosis manifests as a nodule that may ulcerate and spread along the pathway of lymphatic vessels from the distal to the proximal extremities. Histological examination presents with non-specific granulomas of the dermis. PAS, chloramine silver, and gram staining reveal ovoid or fusiform bodies with a positive fungal culture. Due to the presence of multiple nodules, erosions, and ulcers or acute single abscess and cellulitis distributed along the unilateral limb, clinicians should be able to recognize the signs and symptoms of primary cutaneous nocardiosis infection while paying attention to exclude sporotrichosis, mycobacterial infections, and skin tumors, and inquiring the patient for any immunosuppression-related diseases with traumatic history to avoid misdiagnosis.The first-line choice for the treatment of this disease is trimethoprim-sulfamethoxazole (TMP-SMX), where the course of therapy should not be less than 1–3 months. However, reports of sulfonamide-resistant Nocardia infections are increasing year by year, and the treatment plan is adjusted according to the antimicrobial susceptibility testing, which requires continuous and sufficient treatment course.In this case, Nocardia brasiliensis (GenBank accession number: MK177479) was identified by PCR-based sequence analysis by using 16S ribosomal RNA. After the initiation of the specific treatment with levofloxacin and trimethoprim-sulfamethoxazole for 4 weeks, the patient presented with significant clinical improvements. There was no recurrence in the 3-year follow-up period.
Learning Points
Cutaneous Nocardia infection alone has no specific manifestations; however, in combination with other immunodeficiencies, trauma, or poor treatment history, we must consider the possibility of this disease.If a primary cutaneous infection is suspected, a skin biopsy is the most valuable sample.Nocardia is partially slow-growing aerobic actinomycetes. Therefore, the culture time of the bacteria should be extended to avoid misdiagnosis.Sufficient, specific, and sensitive antibiotics can shorten the disease course.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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