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Formalin is commonly thought to decrease the risk of Mycobacterium tuberculosis infection. However, the true disinfection efficacy of formalin for tissue infected with M tuberculosis is unclear. We reviewed all pertinent literature from 1900 until the present regarding the disinfection efficacy of formalin for tissue infected with M tuberculosis. We also retrospectively cultured five cases of M tuberculosis from formalin-fixed archival pulmonary tissue. All cultures from our archived tissue were negative. The literature review revealed limited and contradictory information concerning the viability of M tuberculosis in formalin-fixed human tissue. There are no studies which specifically address the viability of M tuberculosis in tissue exclusively fixed in 10% buffered formalin. The disinfection efficacy of formalin for tuberculosis infected tissue remains unclear. Larger, prospective studies using current methodologies are needed to establish guidelines to ensure the safety for those handling infected, fixed tissue.

The interpretation of atypical leukocytes in the cerebrospinal fluid (CSF) poses diagnostic problems. We present a case of a heart transplant patient whose CSF contained highly atypical lymphocytes that were originally interpreted as "suspicious for lymphoma." Because the patient was clinically thought to have disseminated zoster, he was treated with acyclovir, and the atypical infiltrate resolved. This case exemplifies the extreme difficulty of interpreting cerebrospinal fluid in immunosuppressed patients who are at risk of developing posttransplant lymphoproliferative disorders.

We describe a case of mucinous syringometaplasia in a 53-year-old man. The lesion was located on a previously unreported site, the shaft of the penis. Histologically the lesion contained bland mucinous cells in acrosyringia that extended to the adjacent epidermis. A review of previously reported cases is provided. Even though the name given to this entity implies a reactive nonneoplastic condition, the possibility that this is a benign intraepithelial mucinous neoplasm has not been ruled out. The main differential diagnosis is with extramammary Paget's disease.