What are the signs and symptoms of sporotrichosis?

How to Spot Sporotrichosis

Look for a progressively enlarging papule or nodule at a site of prior trauma that may ulcerate, with or without a characteristic chain of nodules ascending along lymphatic channels—this lymphocutaneous pattern is the hallmark presentation. 1

Classic Clinical Presentations

Lymphocutaneous Sporotrichosis (Most Common)

• Initial lesion: A papule or nodule develops at the inoculation site after a variable incubation period following traumatic contact with soil, decaying vegetation, sphagnum moss, or contaminated animals (especially cats or armadillos) 1, 2
• Ascending nodules: Multiple nodules appear proximally along lymphatic channels in a characteristic linear or "sporotrichoid" pattern—this is the signature finding 2, 3
• Ulceration: The primary nodule and subsequent lymphatic nodules may ulcerate and suppurate 2, 4
• Chronicity: The infection is chronic and indolent, rarely resolving spontaneously 1

Fixed Cutaneous Sporotrichosis

• Infection remains localized to the skin without lymphatic spread 1
• Presents as a single plaque or nodule that may ulcerate at the inoculation site 1

Less Common Forms to Recognize

Pulmonary Sporotrichosis

• Patient profile: Middle-aged men with chronic alcoholism and/or chronic obstructive pulmonary disease 1, 5
• Presentation: Chronic cavitary fibronodular disease on imaging 1, 5
• Prognosis: Poor outcome, often due to delayed diagnosis and severity of underlying lung disease 1, 5

Osteoarticular Sporotrichosis

• Occurs through contiguous spread from cutaneous lesions, direct inoculation, or hematogenous dissemination 6
• Presents as chronic, indolent bone and joint involvement 6
• Diagnosis is often delayed, leading to permanent deformity 6

Disseminated Cutaneous Sporotrichosis

• High-risk patients: Immunosuppressed individuals (AIDS, transplant recipients, those on corticosteroids or TNF antagonists), though can rarely occur in immunocompetent patients 5, 7
• Presentation: Multiple painful ulcerated nodules on face and extremities, often with systemic symptoms (fever, night sweats, weight loss, anorexia) 7
• Critical action: In any immunosuppressed patient with cutaneous or lymphocutaneous disease, actively search for pulmonary and CNS dissemination 5, 8

Key Diagnostic Clues

Epidemiological Red Flags

• Occupational/recreational exposure: Outdoor work involving soil, timber, hay, or sphagnum moss 1, 6
• Zoonotic transmission: Contact with infected cats or scratches from digging animals like armadillos 1, 3
• Geographic distribution: Endemic in tropical and subtropical areas, though outbreaks can occur anywhere 1, 2, 3

Physical Examination Findings

• Skin lesions: Nodular or ulcerated lesions with granulomatous appearance 2, 4
• Lymphatic involvement: Palpable cord-like lymphatic channels with nodules 2, 3
• Absence of systemic symptoms: In uncomplicated cutaneous/lymphocutaneous disease, patients are typically otherwise healthy 1

Common Diagnostic Pitfalls

• Histopathology is often negative: Even with fungal-specific stains, organisms may not be visualized due to the small number present (oval to cigar-shaped yeasts, 3-5 μm diameter) 1, 8
• Culture may be negative: Despite active infection, cultures can fail to grow the organism 5, 8
• Delayed diagnosis in visceral forms: Rarity and similarity to other fungal and mycobacterial infections lead to diagnostic delays 8, 6
• Serological testing has limited utility: Except for meningitis, serology is not useful for diagnosis 1, 8

Diagnostic Confirmation

• Obtain specimens via lesion aspiration, scalpel blade scraping, or tissue biopsy for culture and histopathology 8
• Inoculate on Sabouraud dextrose agar at room temperature; growth typically occurs within 8 days but may require up to 4 weeks 5, 8
• For suspected systemic disease, collect sputum, synovial fluid, or CSF as appropriate 8