Proteomics for the diagnosis of thyroid lesions: preliminary report.

OBJECTIVE: Matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) is a unique proteomic technology that explores the spatial distribution of biomolecules directly in situ, thus integrating molecular and morphological information. The possibility of correlating distribution maps of multiple analyses with cytological features makes it an ideal research tool for discovering new diagnostic markers. A previous study showed that MALDI-IMS could help discrimination between different types of thyroid lesions, especially papillary thyroid carcinoma (PTC); the present feasibility study on ex vivo fine needle aspiration (FNA) smears describes its potential in detecting new proteomic targets of other thyroid lesions (follicular lesions, medullary carcinoma). METHODS: MALDI-IMS was conducted on ex vivo FNAs obtained from surgical specimens and corresponding in vivo samples. Differences between proteomic profiles of different thyroid lesions were compared. RESULTS: Comparing the protein profiles of hyperplastic nodules obtained from three different patients with each other, and with a new PTC, showed a high degree of concordance, indicating good reproducibility of the IMS technology on cytological samples, suggesting its potential as a tool for biomarker discovery. Furthermore, comparison of the average proteomic profiles of hyperplastic nodules with a Hürthle cell adenoma revealed significant differences, underlying the capability of MALDI-IMS to distinguish between different thyroid lesions. Finally, the proteomic profile of medullary thyroid carcinoma was also characterized. CONCLUSIONS: Our results confirmed the possible role of MALDI-IMS in the search for diagnostic targets of PTC and follicular lesions, which could be applied in larger trials aimed at the identification of proteins, convertible to cost-effective diagnostic tools such as immunohistochemistry. These tests could be used to analyse in vivo cytological smears, improving the preoperative diagnosis of indeterminate thyroid nodules.

Primary cutaneous interdigitating dendritic cell sarcoma (IDCS): Report of a new case and literature review.

Interdigitating dendritic cell sarcoma is a very rare entity in the spectrum of histiocytic and dendritic cell neoplasms that mostly occurs in lymph nodes, generally presenting as solitary lymphadenopathy, but may affect every organ. Among extra nodal sites, cutaneous interdigitating dendritic cell sarcoma is exceedingly rare; to date, only 9 cases have been described in English literature. The mean age at diagnosis was 60 years, with a male-female ratio of 1,5 to 1; clinically, two different modalities of skin presentation have been reported: solitary, represented by a single red-brownish nodular lesion, or diffuse, characterized by multiple nodular lesions in one or more body districts. The extreme rarity of this sarcoma and its morphological similarity to other poorly differentiated tumors may lead to a delay in diagnosis; in particular, cutaneous localization may be difficult to differentiate from follicular dendritic cell sarcoma, Langerhans cell sarcoma, poorly differentiated squamous cell carcinoma and more generally sarcomatoid carcinoma, atypical fibroxanthoma, malignant melanoma and several sarcomas. Immunohistochemistry plays an important role in identifying this rare entity and formulating a correct histological diagnosis, fundamental requirement for choosing the best therapeutic approach. We report herein a further case of an 81-year-old Caucasian woman who presented to the Dermatology Department to remove an asymptomatic skin papule in the left temporal region, clinically diagnosed as dermatofibroma. The overall pathological and immunohistochemical features supported the diagnosis of a malignant dendritic cell tumor, consistent of interdigitating dendritic cell sarcoma.