Bipolaris vs Exserohilum: Poroconidia and Hilum
Original bench-card visual comparing two dematiaceous molds with multicelled poroconidia on geniculate conidiophores, separated by the protruding hilum of Exserohilum.
Poroconidia molds: Bipolaris flat hilum vs Exserohilum protruding hilum
Both form multicelled poroconidia on a bent, zig-zag (geniculate) conidiophore. The separator is the hilum: Bipolaris has a slightly flattened scar, Exserohilum has a strongly protruding hilum.
Multicelled oblong poroconidia borne sympodially on a geniculate conidiophore. The hilum is only slightly flattened and does not strongly protrude.
Elongated multicelled poroconidia with a strongly protruding hilum at the base. The projecting hilum is the main separator from Bipolaris.
Multicelled oblong poroconidia borne sympodially on a geniculate conidiophore. The hilum is only slightly flattened and does not strongly protrude.
Elongated multicelled poroconidia with a strongly protruding hilum at the base. The projecting hilum is the main separator from Bipolaris.
Poroconidia comparison anchors
| Visual clue | Meaning | Student shorthand |
|---|---|---|
| Geniculate (zig-zag) conidiophore | Poroconidia group | Sympodial growth bends the conidiophore at each scar |
| Oblong poroconidia, flat hilum | Bipolaris pattern | Hilum slightly flattened, not projecting |
| Elongated conidia, protruding hilum | Exserohilum pattern | Projecting hilum is the key separator |
| Sinus or subcutaneous source | Clinical context | Significance depends on source and host; interpret per SOP |
Poroconidia interpretation guide
| Pattern | What to call it | How to think about it |
|---|---|---|
| Oblong poroconidia, flat hilum | Bipolaris-compatible morphology | Confirm by validated mold ID workflow |
| Elongated poroconidia, protruding hilum | Exserohilum-compatible morphology | Confirm by validated mold ID workflow |
| Muriform conidia with beak | Alternaria pattern | Different conidial structure |
- Bipolaris and Exserohilum are hilum-shape cards.
- A protruding hilum points to Exserohilum; a flat hilum points to Bipolaris.
- Clinical significance depends on specimen source and host context.
Bipolaris = flat hilum. Exserohilum = protruding hilum. Both = geniculate poroconidia.