Solitary extramedullary plasmocytoma of the thyroid: a case report and histological approach to plasma cells infiltrate in the thyroid gland

Fine-needle aspiration cytology for the diagnosis of plasma cell neoplasms in the head and neck region: A systematic analysis of the literature

BACKGROUND

Cytopathologic analysis is feasible and provides detailed morphological characterisation of head and neck lesions.

AIMS

To integrate the available data published on fine-needle aspiration cytology (FNAC) used for the diagnosis of plasma cell neoplasms (PCN) of the head and neck region.

MATERIALS AND METHODS

Searches on PubMed, Web of Science, Embase, and Scopus were performed to compile data from case reports/case series published in English. The Joanna Briggs Institute tool was used for the critical appraisal of studies.

RESULTS

A total of 82 studies comprising 102 patients were included in this review. There was a predilection for men (68.6%) (male/female ratio: 2.1:1). Individuals in their 50s (29.4%), 60s (22.5%), and 70s (22.5%) were more often affected. The thyroid gland (26.2%) was the main anatomical location, followed by scalp (15.5%), neck/cervical region (15.5%), jaws (13.6%), and major salivary glands (13.6%). For FNAC analysis, a smear was employed in 41 (40.6%) cases and a cell block was used in four (3.9%). In 56 (55.4%) reports, no cytological methods were available. Morphologically, 34 (56.7%) cases had a diagnosis of PCN with agreement between cytopathology and histopathology. The rate of wrong diagnoses when using cytology was 27.5%. Immunophenotyping was performed in 49 (48%) of the cases. The 69-month disease-free survival rate was 60.2%, while the 27-month overall survival rate was 64.1%.

CONCLUSION

This study reinforces that FNAC can be an ancillary tool in the first step towards the diagnosis of PCN of the head and neck region, especially when applying a cell block for cytological analysis.

Solitary Extramedullary Plasmacytoma of the Thyroid Gland in a Patient With Subclinical Hyperthyroidism

Objective

Solitary extramedullary plasmacytoma (SEP) of the thyroid is rare, and its clinical and pathologic features are not entirely understood. Generally, patients with SEP of the thyroid also present with Hashimoto thyroiditis. We report, for the first time, a case of SEP of the thyroid in a patient with subclinical hyperthyroidism.

Methods

A 46-year-old woman presented to the emergency department with symptoms consistent with a panic attack. Following a physical examination, neck ultrasonography, and laboratory tests, we determined that the patient was hyperthyroid and possessed a toxic multinodular goiter. The patient elected to undergo a total thyroidectomy to treat the subclinical hyperthyroidism and to remove the nodules.

Results

SEP diagnosis requires consideration of the systemic spread of multiple myeloma and a combination of immunohistochemical examination, imaging, and other laboratory tests. Upon further examination, we confirmed SEP through the following criteria: the absence of kidney failure or hypercalcemia, a biopsy demonstrating plasma cell histology, a lack of bone or tissue involvement, and low serum myeloma protein concentration. The immunophenotype of the tumor cells further confirmed SEP diagnosis, with positivity for CD138, CD79a, and lambda light chain antibodies and no reactivity toward cyclin D1.

Conclusion

This case fulfilled the criteria for SEP, and we were able to rule out multiple myeloma. Currently, no standard treatment exists for SEP. Yet, the prognosis remains encouraging. Going forward, SEP of the thyroid should be considered in the differential diagnosis of a patient with subclinical hyperthyroidism and a toxic multinodular goiter.

A Case Report of Thyroid Plasmacytoma and Literature Update

Plasmacytomas of the thyroid gland are rare, whether or not they arise as solitary (primary) lesions or secondary to systemic multiple myeloma. Here, we present the case of a 71-year-old female presenting with goiter and Hashimoto’s thyroiditis, in whom the subsequent histopathological diagnosis of plasmacytoma was a surprise. In presenting this case, we summarize the last 25 years of literature on thyroid plasmacytoma and review the salient clinicopathological characteristics, differential diagnoses, management, and outcomes of this rare condition.