Disseminated rhinosporidiosis masquerading as soft tissue round cell tumour diagnosed by fine needle aspiration cytology.

Rhinosporidium seeberi belongs to the eukaryotic class Mesomycetozoea and causes chronic granulomatous lesions known as rhinosporidiosis. Rhinosporidiosis frequently involves the nasal cavity and nasopharynx through transepithelial invasion. Atypical presentations of this disease at other body sites have been reported, including the subcutis, visceral organs, bones, and genitals. Only a few cases of cutaneous and subcutaneous involvement have been reported to date. This chronic granulomatous condition is known for its recurrence following autoinoculation unless the correct diagnosis and appropriate treatment are given. We describe a case of an immunocompetent adult who had undergone fine needle aspiration cytology (FNAC) of mass-like swellings in the right thigh and right calf at another healthcare centre and had been diagnosed with a small round blue cell tumour. FNAC at our centre confirmed a rare case of rhinosporidiosis that was clinically mimicking a soft tissue neoplasm of the lower extremity, and the erroneous interpretation of the prior cytology studies had resulted in misinterpretation of the individually dispersed pathogenic organisms as individual malignant cells. FNAC of rhinosporidiosis can lead to early diagnosis and prompt treatment of this pathogen when it presents at unanticipated body sites.

CSF Involvement by Nonhematolymphoid Malignancies: A Descriptive Study with Emphasis on Cytomorphological Clues.

Introduction: Detection of malignant cells in cerebrospinal fluid (CSF) samples in suspected cases of malignancy is critical for the management of patients. CSF involvement by nonhaematolymphoid malignancies is less common. We aimed to study the cytomorphologic characteristics of various nonhaematolymphoid malignancies in CSF. Methods: A retrospective cytomorphological analysis of 27 CSF cytology smears reported as positive or suspicious for nonhematolymphoid malignancies from January 2010 to April 2020 over 10 years was carried out. Smears in all cases were prepared by cytospin technique and stained with May-Grunwald-Giemsa (MGG) and papanicolaou (Pap) staining procedures. Cell immunohistochemistry/immunocytochemistry was done wherever cell block/extra slides were available. Results: Twenty-four of 27 cases were interpreted as "positive," while three were reported as "suspicious" of malignancy. Nineteen of 27 cases were metastatic adenocarcinomas including three suspicious malignancy cases with the primary sites of origin being the breast (10), stomach (2), rectum (1), gall bladder (1), lung (1), and four cases of unknown primary. Of the remaining positive cases, there were five cases of metastatic medulloblastoma, two cases of metastatic pineoblastomas, and one case of metastatic extraskeletal Ewings sarcoma. Each of these metastatic malignancies had at least a single diagnostic cytomorphological clue, similar to those observed in other body cavities and primary malignancy sites. Conclusion: Nonhematolymphoid malignancies are readily diagnosable on CSF cytology, most of them are metastatic. Identification of malignant cells in CSF is critical, as it has therapeutic and prognostic implications.