Merciful anosmia is a condition in which the person is unaware of a foul smell emanating from their own

nose A nose is a sensory organ and respiratory structure in vertebrates. It consists of a nasal cavity inside the head, and an external nose on the face. The external nose houses the nostrils, or nares, a pair of tubes providing airflow through the ...

. This condition is seen in

atrophic rhinitis Chronic atrophic rhinitis (often simply atrophic rhinitis) is a chronic inflammation of the nose characterised by atrophy of nasal mucosa, including the glands, turbinate bones and the nerve elements supplying the nose. Chronic atrophic rhinit ...

. In atrophic rhinitis, the

turbinates In anatomy, a nasal concha (; : conchae; ; Latin for 'shell'), also called a nasal turbinate or turbinal, is a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various other animals. The conc ...

, venous

sinusoids A capillary is a small blood vessel, from 5 to 10 micrometres in diameter, and is part of the microcirculation system. Capillaries are microvessels and the smallest blood vessels in the body. They are composed of only the tunica intima (the inn ...

, seromucinous glands and nerves undergo

atrophy Atrophy is the partial or complete wasting away of a part of the body. Causes of atrophy include mutations (which can destroy the gene to build up the organ), malnutrition, poor nourishment, poor circulatory system, circulation, loss of hormone, ...

, resulting in a foul smelling discharge. As the

nerve fibres An axon (from Greek ἄξων ''áxōn'', axis) or nerve fiber (or nerve fibre: see spelling differences) is a long, slender projection of a nerve cell, or neuron, in vertebrates, that typically conducts electrical impulses known as action pote ...

sensing smell are also atrophied, the patient is unable to appreciate the foul smell.

References

Symptoms and signs: Respiratory system Upper respiratory tract diseases {{med-sign-stub