Tyrosine crystals in Nasolabial cyst – A morphologic curiosity diagnosed at cytology

Background: Tyrosine rich crystals (TC) are curious structures, rarely encountered at histopathology, more so at cytology. These crystals have been documented exceptionally in various non-neoplastic and neoplastic lesions of salivary gland, lacrimal gland and rarely in larynx. The finding of these crystals in nasolabial cyst has not been reported till date.

Case: A 35-year-old female with a clinical and radiologic diagnosis of nasolabial cyst underwent fine needle aspiration cytology (FNAC). Tyrosine crystals in singles and in groups assuming ‘petaloid’ and ‘daisy head’ forms were noted along with few lymphocytes and histiocytes. Amylase crystals were also noted.

Conclusion:  Regardless of the precise cause, cytologic recognition of TC is important to avoid confusion. Identification of these crystals at FNAC is a matter of avid observation and encourages cytopathologist for meticulous examination of all fluids. The case also highlights that the occurrence of TC is not restricted to SG and the circumstances in which it occurs is diversified.