Sporotrichoid Primary Cutaneous Nocardiosis: A Rare Case of Isolated Upper-Limb Involvement in a Housewife

Abstract

Nocardiosis is a rare infection due to a ubiquitous, gram-positive, weakly acid-fast, filamentous, aerobic bacteria, that are usually responsible for opportunistic infection in immunocompromised patients. Less frequently, nocardiosis can affect immunocompetent patients, causing primary cutaneous infections. Here we present a case of a 45-year-old housewife with a 12-day history of red painful nodules arranged linearly on her right upper limb, without any apparent history of injuries or comorbidities, albeit with a hobby of gardening. The unusual yet characteristic presentation, microbiological findings, and excellent response to co-trimoxazole therapy were consistent with a diagnosis of sporotrichoid primary cutaneous nocardiosis. The uncommon lymphocutaneous presentation is often misdiagnosed. Therefore, keeping a high index of suspicion in such cases is important to improve the cure rate and prevent complications.

Introduction

Nocardiosis is primarily a disease affecting the lungs (most commonly in immunocompromised) but primary cutaneous nocardiosis (most commonly in immunocompetent) constitutes up to a quarter of all cases.[1,2]

Here, we report a case of primary sporotrichoid cutaneous nocardiosis, which is rarely reported in India.[3]

Case Report

A 45-year-old housewife presented with multiple painful reddish swellings on the right upper extremity for 12 days, with onset over mid-forearm and linear extension up to mid-arm [Figure 1].

Figure 1.

Multiple, linear, well defined, discrete, and erythematous nodules over the right upper limb

There was no history of trauma, insect bite, or injury from a thorn/plant, although she had a hobby of gardening.

There was no history of hypertension, atopy, diabetes, weight loss, fever, loss of appetite, malignancy, organ transplantation, use of immunosuppressants, any other history suggestive of immunosuppression, recent travel, or similar family history.

Cutaneous examination revealed multiple, well defined, discrete, tender, warm, and erythematous nodules of 1–2 cm size, with superimposed purulent, non-grainy discharge, and ulceration in few, extending linearly from the flexor aspect of the right mid-arm to extensor aspect of mid-forearm. There were no sinuses. Axillary lymph nodes were palpable and tender.

Clinical differential diagnoses of sporotrichosis, nocardiosis, mycetoma, atypical mycobacteria, cutaneous tuberculosis, leishmaniasis, and malignancies were considered.

Staining from pus revealed multiple, gram-positive, branching filamentous bacilli with ‘sunray appearance’ in a few fields, which were partially acid-fast on a modified Kinyoun technique (using 1% sulphuric acid) [Figure 2] but negative on 10% potassium hydroxide (KOH) mount. Culture showed multiple discrete, chalky white, wrinkled colonies on day 3 in blood agar [Figure 3] and day 9 on the Lowenstein Jenson medium. McConkey and Sabouraud dextrose agar showed no growth. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) was inconclusive for species identification.

Figure 2.

Partially acid-fast, thin, filamentous Nocardia bacilli on modified Kinyoun staining (using 1% sulphuric acid as decolorizer)

Figure 3.

Characteristic multiple, dry, chalky white, opaque colonies of Nocardia on blood agar (after 72 hours of incubation at 35°C)

Histopathology of a nodule over the forearm revealed focal dyskeratosis, elongation of rete pegs, pigment incontinence, and a dense dermal lympho-mononuclear infiltrate necrotizing the fibro-lamellar architecture [Figure 4].

Figure 4.

Focal dyskeratosis, elongation of rete pegs, pigment incontinence, and dense dermal lympho-mononuclear infiltrate (H and E, 10X)

Hematological, biochemical, and radiological investigations did not reveal any comorbidities or immunosuppression (ELISA for HIV I and II was non-reactive). A radiograph of the lesional site showed soft tissue swelling but no bony involvement.

The characteristic clinical and microbiological features confirmed the diagnosis of a sporotrichoid pattern of cutaneous nocardiosis.

There was a partial response with an initial empirical treatment with amoxicillin clavulanate 625 mg thrice daily for 5 days and topical fusidic acid [Figure 5a]. After confirmation of diagnosis, cotrimoxazole therapy in a dose of trimethoprim 160 mg and sulphamethoxazole 800 mg twice daily was started, based on the majority of reports from India and worldwide indicating high efficacy and low resistance of cotrimoxazole in cutaneous nocardiosis. Excellent results were observed within 10 days of therapy [Figure 5b], with complete healing (with minimal scarring) seen within 12 weeks. There was no recurrence till 6 months of follow-up.

Figure 5.

(a) Partial improvement after 5 days of empirical treatment with amoxicillin clavulanate 625 mg TID (b) Excellent response of cutaneous nocardiosis after 12 weeks of treatment with cotrimoxazole (800/160 mg BD)

Discussion

The first description of Nocardia came from a French veterinarian, Edmond Nocard, in 1888, in relation to bovine farcy.[3] More than 80 species of Nocardia can be pathogenic to humans, of which N. braziliensis (80%) is the most common in skin infections.[2,3,4]

Nocardia are found worldwide as saprophytes in soil, decaying vegetable material, and water.[5,6] Thereby, minor local trauma due to thorn pricks during gardening, farming, or even barefoot walking can inoculate the infection. Exceptionally, the infection may transmit via dust, iatrogenic sources, or even an insect bite/sting, as reported by Lovecchio et al.[4,5,6]

The most common infection is pulmonary nocardiosis, accounting for 80% of the cases. It is found in immunosuppressed patients with risk factors like AIDS, malignancies, immunosuppressants, diabetes mellitus, organ transplantation, and renal diseases.[4]

Primary cutaneous nocardiosis is rare and typically, but not always, a disease of the immunocompetent, as in our case. Three clinical variants of primary cutaneous nocardiosis have been identified: (1) Mycetoma (most common); (2) Superficial skin infections such as cellulitis, abscesses, and ulcers; and (3) Lymphocutaneous/sporotrichoid (rarest).[3,5]

A 12% incidence was reported in a 24-year Spanish survey.[7] The incidence in India is unknown, but only a countable number of cases have been reported so far.[1,3] It is perhaps not so rare in India, but it is under-recognized and under-reported.

Among the few previously reported cases in India [Table 1], the majority of the patients were young to middle-aged males, mostly rural farmers. Whereas our patient was a housewife living in an urban locality without a farming background, albeit with the gardening hobby. Inamadar et al. reported a similar case, though after a definite botanical injury.[1] Most of the earlier reported patients had lower extremity involvement, while our patient had isolated upper extremity involvement.[3] Occurrences over atypical sites like the forehead and neck have been reported.[2,6]

Table 1.

Cutaneous nocardiosis case reports from India

Age (in years)	Sex	Occupation	Site	Modified AFB stain	Response to cotrimoxazole	Reported by
16	Male	Agriculturist	Right leg	+	Complete	Inamadar et al.[1]
30	Male	Agriculturist	-	+	Complete	Inamadar et al.[1]
37	Male	Agriculturist	Left leg, right elbow	+	Complete	Bosamiya et al.[3]
26	Male	Agriculturist	Right leg	+	Complete	Baradkar et al.[4]
71	Male	Laborer	Left hand and forearm	+	Complete	Sharma et al.[5]
31	Female	-	Right gluteal and lumbosacral	+	Complete	Sharma et al.[5]
22	Male	Agriculturist	Right lower limb	+	Complete	Ramani et al.[9]
19	Male	-	Right side of groin	+	Complete	Belliappa et al.[10]
45	Female	Housewife	Right forearm, arm	+	Complete	Present report

The differential diagnosis for the sporotrichoid pattern most commonly includes sporotrichosis, atypical mycobacterial infections (marinum/chelonae/kansasii), leishmaniasis, cryptococcosis, tuberculosis, epithelioid sarcoma, and staphylococcal pyoderma.[1,2,3,5]

Nocardia is difficult to grow in culture due to its slow-growing nature. But the definitive diagnosis can only be made with isolation from culture, as in our case.[6] Faster diagnosis can be obtained by using specialized media like buffered charcoal agar, polymerase chain reaction and/or MALDI-TOF.[6,8]

The cornerstone of treatment remains cotrimoxazole (trimethoprim-sulfamethoxazole) for 3–6 months, as in our case. Shorter courses may be effective in immunocompetent but carry a higher incidence of relapse and metastatic abscesses.[3,6] The majority of studies indicate high efficacy of cotrimoxazole (susceptible isolates ranging from 98 to 100%), though few studies have reported resistant isolates, particularly in a few rare species such as N. farcinica (up to 80% resistance to cotrimoxazole).[11] Alternative drugs like amikacin, minocycline, imipenem, third-generation cephalosporins, and linezolid can be used in cases of sulfonamide hypersensitivity or poor tolerance.[2,3,4]

Conclusion

Nocardiosis is frequently mistaken for other sporotrichoid conditions. The diagnosis of this rare condition can be even more difficult in the absence of agricultural exposure. Therefore, a high index of suspicion and a comprehensive microbiological examination is key to effectively managing nocardiosis and avoiding complications, as in our case.

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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.