Question
Sporotrichosis
Answer
Sporotrichosis is a chronic, subacute fungal infection caused by Sporothrix schenckii, a dimorphic fungus found in soil, decaying vegetation, and plant material (thorns, rose bushes, sphagnum moss) — “rose gardener’s disease.”
Transmission: traumatic inoculation via a thorn prick, splinter, or other penetrating injury involving contaminated plant material.
Clinical form — lymphocutaneous sporotrichosis (most common): a painless nodule develops at the inoculation site, ulcerates, and the infection spreads proximally along lymphatic channels, producing a chain of secondary nodules — a highly characteristic pattern.
Other forms: fixed cutaneous sporotrichosis (localized, without lymphatic spread); disseminated/systemic sporotrichosis (rare, in immunocompromised hosts).
Laboratory diagnosis: culture is the gold standard — grows as a mould at 25°C, converting to a yeast form at 37°C (thermal dimorphism); direct microscopy of tissue is often unhelpful since organisms are typically scanty; histopathology may show characteristic asteroid bodies.
Treatment: itraconazole for lymphocutaneous/cutaneous disease; saturated solution of potassium iodide as an older alternative; amphotericin B for severe/disseminated disease.