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Green Nail Syndrome Following HFMD–Induced Onychomadesis in a Pediatric Patient

Case Studies 6 min 13

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Created On: 21/09/2026

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Poster abstract

Green nail syndrome (GNS), also termed as chloronychia, is an uncommon Pseudomonas aeruginosa-mediated nail infection that is rarely encountered in children. It is typically associated with recognized predisposing factors such as artificial nails, occlusion, trauma, or immunocompromise. A previously healthy 6-year-old female developed multi-digit onychomadesis several weeks after an episode of hand, foot, and mouth disease (HFMD). This was subsequently followed by the appearance of green discoloration confined to both great toenails.

Clinical examination depicted well-circumscribed green to yellow-green chromonychia of the bilateral great toenails together with proximal separation of several fingernail and toenail plates from the nail matrix. The diagnosis of GNS complicating HFMD-associated onychomadesis was established on classic clinical morphology, without microbiological culture. The patient lacked any of the risk factors typically reported in pediatric cases.

Management consisted of topical antipseudomonal therapy alone, with expectant management of the underlying onychomadesis. Follow-up demonstrated normalization of nail coloration and continued nail regrowth, with only minor residual nail changes. This case highlights transient nail matrix disruption from a common pediatric viral illness, which may independently predispose to opportunistic Pseudomonas colonization, even in an immunocompetent host. This reinforces the value of clinical pattern recognition in diagnosing GNS.

Complaints

Painless loosening of several fingernails noted by the patient's mother, preceding frank nail plate detachment.
Progressive proximal separation of multiple fingernail and toenail plates over several weeks.
New-onset green discoloration confined to both great toenails.

Anamnesis

Introduction

HFMD is a common viral illness in children, typically triggered by Coxsackievirus A16 or enterovirus 71. Coxsackievirus A6 has also emerged as an important cause of atypical clinical presentations. Onychomadesis, a transient arrest of nail matrix activity leading to proximal nail plate separation, is a recognized delayed sequela of HFMD that typically emerges four to six weeks after the acute illness and resolves spontaneously. GNS is mediated by subungual colonization with Pseudomonas aeruginosa and classically develops in the setting of chronic moisture exposure, distal onycholysis, or underlying nail ailment. It is predominantly a condition of middle-aged and older adults, and pediatric cases are exceptionally rare, most often occurring in the context of immunocompromise.

A previously healthy 6-year-old female presented with an unusual pattern of progressive, painless nail detachment following an uncomplicated episode of HFMD, as depicted below:

Illness timeline

Approximately 1 month before presentation: Developed HFMD, marked by oral ulcerations and acral vesicular lesions. The acute illness resolved without complications.
Shortly after resolution: Painless loosening of the fingernails was noted.
Over the following weeks: Progressive proximal detachment of several fingernail and toenail plates developed.
Subsequent weeks: The patient's mother observed green discoloration of the toenails.

Associated symptoms

No fever, fatigue, or other systemic symptoms reported.
No pain or pruritus associated with the affected nails.

Exposure history

No recent aquatic exposure.
No recent travel.

Examination

(a) Toenail findings

Bilateral great toenails: Distinct green to yellow-green nail discoloration with well-defined margins, suggestive of GNS.

(b) Fingernail and additional toenail findings

Multiple fingernails and toenails bilaterally; onychomadesis with complete proximal detachment of the nail plate from the nail matrix.
Early nail regrowth with melanonychia striata; no erythema, crusting, or secondary chromonychia.
Affected nails non-tender to palpation.

Diagnosis: HFMD-associated onychomadesis complicated by Pseudomonas aeruginosa nail infection (GNS), established on classic clinical morphology.

Treatment

(a) Definitive treatment

Topical gentamicin 0.1% ointment (aminoglycoside antibiotic) was prescribed, applied once daily to the affected toenails. The coexisting onychomadesis was managed expectantly, consistent with its typically self-limited course, without additional intervention.

(b) Follow-up and monitoring

The patient was scheduled for outpatient follow-up to monitor nail regrowth and resolution of chromonychia. Instructions were provided to seek re-evaluation if pain, spreading discoloration, or soft-tissue involvement developed.

Results

Follow-up findings

Normalization of nail coloration across the previously affected toenails.
Ongoing proximal nail plate regrowth.
Progressive resolution of onychomadesis involving multiple toenails.
Mild residual periungual scaling and nail dystrophy observed on follow-up examination.
No recurrence of chromonychia or secondary nail infection.

These findings indicate a favorable clinical response to topical antipseudomonal therapy, with resolution of the active infection. Ongoing, though not yet complete, normalization of nail architecture was observed at the time of follow-up.

Key learnings

Pediatric GNS is rare and is typically reported in association with recognized risk factors such as artificial nails, trauma, occlusion, or immunocompromise.
Onychomadesis may independently create a moist, protected subungual microenvironment that predisposes to opportunistic Pseudomonas aeruginosa colonization.
Classic clinical morphology can support a diagnosis of GNS without requiring microbiological culture in straightforward presentations.
Topical antipseudomonal therapy alone can achieve meaningful clinical improvement in uncomplicated pediatric cases.
Clinicians evaluating children with HFMD-associated onychomadesis should maintain a high index of suspicion for secondary GNS. They should also counsel on nail hygiene during the recovery period.