Can direct immunofluorescence testing still be accurate if performed on biopsy specimens after brief inadvertent immersion in formalin?

BACKGROUND: Direct immunofluorescence is useful in the diagnosis of autoimmune, vesiculobullous, and connective tissue diseases. Michel medium is typically indicated for transport, but clinicians may inadvertently place samples into formalin. OBJECTIVE: We set out to determine the amount of time that specimens can remain in 10% buffered formalin and still retain their diagnostic properties. METHODS: Biopsy samples were examined from cases with established diagnoses of bullous pemphigoid (n = 12), dermatitis herpetiformis (n = 6), and pemphigus vulgaris (n = 6) and exposed to formalin for time points ranging from 2 minutes to 4 hours. RESULTS: We found that immunoreactants were detectable in the majority of samples when subjected to 2 minutes of formalin exposure. Dermatitis herpetiformis and pemphigoid samples retained immunogenicity for 10 minutes, whereas pemphigus showed reduced immunogenicity for all samples studied. A nonimmunologic nuclear fluorochroming pattern was noted in some of the specimens after formalin immersion. LIMITATIONS: Sample size, only examining 3 disease processes, and samples already having been in Michel medium were the major limitations in the study. CONCLUSION: In direct immunofluorescence studies, formalin exposure to biopsy specimens causes two types of artifactual changes: (1) the shortest exposure (2 minutes) causes complete loss of diagnostic markers of pemphigus; and (2) prolonged exposure changes tissue to a form that allows fluorescein-labeled antibodies to give fluorochroming reactions of nuclei (which can be mistaken for in vivo antinuclear antibody reactions of lupus erythematosus). After time intervals of 10 minutes to 2 hours, direct immunofluorescence studies of proven cases of bullous pemphigoid and dermatitis herpetiformis retained variable levels of specific reactivity.

Furuncular myiasis: a case report.

Most clinicians associate myiasis with travel to a tropical location. We report a case of endemic myiasis due to Cuterebra species to remind clinicians that myiasis can occur throughout North America.

Nodular lymphangitis: Report of a case with presentation of a diagnostic paradigm.

A 54-year-old man with asthma, mitral valve prolapse, and a back injury developed erythematous nodules that progressed along the lymphatic drainage of his right arm. Skin biopsy revealed granulomatous inflammation with microabscess formation. Culture confirmed Mycobacterium marinum infection. The patient was treated with clarithromycin, ethambutol, rifampin, and topical silver sulfadiazine. Oral doxycycline hyclate was later added because of slow healing. Mycobacterium marinum is one of a group of infectious agents that can cause nodular lymphangitis. Sporotrichoid lesions most commonly develop after cutaneous inoculation with Sporothrix schenckii, Leishmania species, Nocardia species, and Mycobacterium marinum. A thorough clinical history and physical examination can narrow the differential diagnosis by eliciting information about the etiologic setting, incubation time, clinical appearance of the lesions, and presence or absence of systemic involvement for each of the causative organisms. Skin biopsy and microbiological tissue cultures are essential for diagnostic confirmation. The differential diagnosis and a suggested diagnostic paradigm will be reviewed.

Vesiculopustular eruption associated with transient myeloproliferative disorder.

Transient myeloproliferative disorder (TMD) is a hematologic abnormality usually associated with Down syndrome that may present with a skin eruption in addition to typical systemic findings. We report a case of a patient with TMD and a vesiculopustular eruption without the phenotypic characteristics of Down syndrome who was found to have mosaic trisomy 21. Mutations of the globin transcription factor 1 gene, GATA1, are associated with both TMD and acute megakaryocytic leukemia. Transient myeloproliferative disorder typically presents with pancytopenia, hepatosplenomegaly, and immature circulating white blood cells, and affects approximately 10% of neonates with Down syndrome. These abnormalities rapidly regress within the first few months of life. However, 20% to 30% of neonates with Down syndrome and TMD later develop leukemia. The tumor antigen PRAME (preferentially expressed antigen in melanoma) may serve as a marker for leukemic transformation. We report an illustrative case to alert clinicians about this uncommon cause of vesiculopustular eruption in a neonate without the phenotypic characteristics of Down syndrome and review the clinical findings and laboratory studies that aid in accurate diagnosis.

A case of bullous disease limited to the skin illustrates the spectrum of neoplasia-induced autoimmunity.

Although the initial report of paraneoplastic pemphigus described individuals with mucocutaneous blistering disease, subsequent reports identified patients with lichen planus or graft versus host disease-like changes. We describe a patient with fatal autoimmune blistering disease with absence of mucous membrane lesions. The pattern of complement indirect immunofluoresence helped identify the prognosis prospectively. This case illustrates yet another presentation of the neoplasia-induced autoimmunity.