Approach: This woman has the classic triad of atrophic rhinitis: nasal obstruction, greenish-black foul crusts over turbinate and septum, and merciful anosmia (loss of smell due to atrophy of olfactory nerve endings).
Pathophysiology: In atrophic rhinitis, there is progressive atrophy of the nasal mucosa including seromucinous glands, turbinate bones, and nerve elements. Atrophy of turbinate bones causes them to shrink, paradoxically making the nasal cavity wide and roomy despite complaints of obstruction.
Key examination finding: On speculum examination, the nasal cavity appears abnormally large (roomy). The turbinates are small and shrunken. Dry, greenish-black crusts are visible. When crusts are removed, the underlying mucosa may bleed (epistaxis).
Why other options are wrong:
- Hypertrophied inferior turbinate: seen in hypertrophic rhinitis, not atrophic rhinitis
- Polyp: seen in allergic rhinitis or sinusitis
- Foreign antibody: not a clinical examination sign
The hallmark finding in atrophic rhinitis on examination is the roomy nasal cavity. \[\boxed{\text{Roomy nasal cavity}}\]