Deposition of calcium salts in a case of pulmonary zygomycosis: histopathologic and chemical findings

Localized calcium oxalate crystals in primary cutaneous aspergillosis

Select Aspergillus species can produce oxalate as a fermentation byproduct, which may react with calcium ions to produce insoluble calcium oxalate crystals in tissues. These crystals are frequently associated with pulmonary Aspergillus infections, yet are rarely described in primary cutaneous aspergillosis. Herein, we report the presence of calcium oxalate crystals detected on cutaneous specimens from primary cutaneous Aspergillus niger and Aspergillus fumigatus infections in an immunocompromised, premature infant. No metabolic sources of oxalosis were found.

A retrospective study of the prevalence of calcium oxalate crystals in veterinary Aspergillus cases

Fungi in the genus Aspergillus are some of the most common fungal pathogens in veterinary species, primarily affecting the respiratory tract. In both human and veterinary cases, calcium oxalate crystals have been documented in sites of Aspergillus infection. Cases in multiple species (16 birds, 15 horses, 5 dogs, 1 ox, and 1 dolphin) were identified that had either positive cultures for Aspergillus sp., or had conidiophores present that could be identified as belonging to the genus Aspergillus. Histologic slides were examined to confirm the presence of oxalate crystals and how often they were identified on the original report. Calcium oxalate deposition was detected in 14 of 38 cases examined, including A. fumigatus, A. versicolor, A. niger, and unspecified Aspergillus sp. infections. Calcium oxalate crystals were identified in 11 of 16 avian cases, as well as in 1 of 1 bovine, 1 of 15 equine, and 1 of 5 canine cases. Crystals were described in only 3 of the 14 original pathology reports of these cases, indicating that identification and reporting of crystals in histologic specimens could be improved. All the tissues with crystals were respiratory tissues with air interfaces, including nasal sinus, trachea, syrinx, lung, and air sac. In cases with crystals identified on H&E-stained sections, crystals were frequently not present or were fewer in number in tissue sections stained with Gomori methenamine silver and periodic acid-Schiff. Routine polarization of slides of fungal infections, especially in the respiratory tract, should be considered to check for calcium oxalate crystals.

Corpora Amylacea of Brain Tissue from Neurodegenerative Diseases Are Stained with Specific Antifungal Antibodies

The origin and potential function of corpora amylacea (CA) remains largely unknown. Low numbers of CA are detected in the aging brain of normal individuals but they are abundant in the central nervous system of patients with neurodegenerative diseases. In the present study, we show that CA from patients diagnosed with Alzheimer's disease (AD) contain fungal proteins as detected by immunohistochemistry analyses. Accordingly, CA were labeled with different anti-fungal antibodies at the external surface, whereas the central portion composed of calcium salts contain less proteins. Detection of fungal proteins was achieved using a number of antibodies raised against different fungal species, which indicated cross-reactivity between the fungal proteins present in CA and the antibodies employed. Importantly, these antibodies do not immunoreact with cellular proteins. Additionally, CNS samples from patients diagnosed with amyotrophic lateral sclerosis (ALS) and Parkinson's disease (PD) also contained CA that were immunoreactive with a range of antifungal antibodies. However, CA were less abundant in ALS or PD patients as compared to CNS samples from AD. By contrast, CA from brain tissue of control subjects were almost devoid of fungal immunoreactivity. These observations are consistent with the concept that CA associate with fungal infections and may contribute to the elucidation of the origin of CA.

The Movat Pentachrome Stain as a Means of Identifying Microcrystalline Cellulose Among Other Particulates Found in Lung Tissue

Context.—Microcrystalline cellulose (MCC) is extensively used as a filler material in pharmaceutical tablets. When injected intravenously in aqueous tablet suspensions, MCC may contribute to embolic pulmonary hypertension and be identified histologically in lung tissue samples. In this study, we evaluated a modified Russell Movat pentachrome stain (MMPS) as a means of recognizing MCC and distinguishing it from other birefringent crystals in lung specimens.

Objective.—To study the staining properties of MCC versus other crystalline materials using the MMPS stain.

Design.—Archival, formalin-fixed, paraffin-embedded lung specimens that contained birefringent crystals, including MCC (3 cases of intravenous drug abuse), talc (2 cases of intravenous drug abuse, 1 talc pleurodesis), mixed silicates (1 case of silicate pneumoconiosis), and calcium oxalate (1 case of aspergillosis from Aspergillus niger infection), were evaluated with MMPS. Crystal identification was confirmed by morphology, other histochemical stains, infrared spectroscopy (1 case), and cellulose controls.

Results.—The MMPS stained the MCC bright yellow in tissue and control specimens. Talc stained light greenish-blue; mixed silicates appeared either greenish-blue or unstained. Oxalate crystals stained sea-green. Crospovidone, a nonbirefringent tablet filler substance, stained yellow to dark green with MMPS and was easily distinguished from MCC. Starch granules were unstained by MMPS.

Conclusions.—The MMPS is an excellent method for the histochemical identification of MCC in tissue and its separation from other birefringent crystals with which MCC might be confused. The MMPS is especially useful in the evaluation of pulmonary foreign body embolization in cases of suspected intravenous substance abuse.