Fine-needle aspiration of primary Langerhans cell histiocytosis of the thyroid gland, a potential mimic of papillary thyroid carcinoma

Langerhans cell histiocytosis of thyroid and bilateral parotid diagnosed on fine needle aspiration cytology

LCH has a distinct site predilection and cytological feature. However, it can cause diagnostic difficulties at unusual sites or deviated cytomorphology. FNAC is a minimally invasive procedure that can be performed in any organ (parotid and thyroid where biopsy is not commonly indicated) and multiple sites/organs simultaneously for diagnosis. FNA sampling can also help with cell block preparation for performing immunohistochemistry and molecular studies if necessary.

Analysis of thyroid involvement in children and adult Langerhans cell histiocytosis: An underestimated endocrine manifestation

BACKGROUND

Langerhans cell histiocytosis (LCH) is a rare disease caused by the clonal expansion of CD1a+/CD207+ LCH cells. The thyroid involvement in LCH has mostly been described in case reports.

METHODS

We retrospectively evaluated the clinical characteristics, diagnosis, and treatment of 27 children and adult patients with thyroid LCH in our center between 2010 and 2021.

RESULTS

The incidence of thyroid LCH was 14.00% (7/50) in children and 10.10% (20/198) in adults, respectively. Among patients with thyroid involvement, 81.5% presented with diabetes insipidus (DI) as the first symptom, and 51.9% complained of neck swelling or mass. Children and adults with thyroid LCH had higher frequencies of the hypothalamic-pituitary axis (HPA) (children: 100% vs. 62.8%, P=0.05; adult: 95% vs. 42.1%, P<0.001), the lung (children: 85.7% vs. 25.6%, P=0.004; adult: 70% vs. 50.6%, P=0.099), and a lower frequency of bone (children: 14.3% vs. 55.8%, P=0.049; adult: 45% vs. 73.6%, P=0.008) involvement than patients without thyroid involvement. Patients with thyroid LCH had a higher frequency of primary hypothyroidism and a lower frequency of euthyroidism than patients without it. The two major types of ultrasound imaging were diffuse (55%) and nodular type (45%). The standardized uptake value of thyroid on 18-F-fluorodeoxyglucose positron emission tomography/computed tomography was 5.3-12.8. The diagnoses were confirmed using thyroid aspiration (54.5%) or surgery (45.5%). In addition, thyroid LCH combined with papillary thyroid carcinoma was not rare (2/27).

CONCLUSION

Thyroid involvement in LCH is not rare. Furthermore, identifying thyroid involvement can facilitate the pathological diagnosis of LCH. Therefore, the possibility of thyroid LCH should be fully investigated in patients with DI, primary hypothyroidism, abnormal thyroid ultrasound results, and multi-system disease. In addition, thyroid aspiration can confirm suspected thyroid LCH. Finally, special attention should be paid to evaluating HPA and pulmonary involvement in thyroid LCH.

Immunocytochemistry for diagnostic cytopathology-A practical guide

Cytological specimens, which are obtained by minimally invasive methods, are an excellent source of diagnostic material. Sometimes they are the only material available for diagnosis as well as for prognostic/predictive markers. When cytomorphology is not straightforward, ancillary tests may be required for a definitive diagnosis to guide clinical management. Immunocytochemistry (ICC) is the most common and practical ancillary tool used to reach a diagnosis when cytomorphology is equivocal, to differentiate entities with overlapping morphological features, and to determine the cell lineage and the site of origin of a metastatic neoplasm. Numerous immunomarkers are available, and some are expressed in multiple neoplasms. To rule out entities within a differential diagnosis, the use of more than one marker, sometimes panels, is necessary. ICC panels for diagnostic purposes should be customised based on the clinical context and cytomorphology, and the markers should be used judiciously to preserve material for additional tests for targeted therapies in the appropriate setting. This review offers a practical guide for the use of ICC for diagnostic cytopathology, covering the most commonly encountered non-hematolymphoid diagnostic scenarios in various body sites.

Cytologic and histological features of rare nonepithelial and nonlymphoid tumors of the thyroid

Thyroid tumors can be classified into epithelial, nonepithelial, and nonprimary lesions. Nonepithelial thyroid tumors are rare. They can be of primary origin within the thyroid gland, arise secondary to contiguous growth from adjacent tissues, or represent metastatic disease. The incidence of nonepithelial tumors of the thyroid is only 1% to 2%, most of which are lymphomas; the remainder includes mesenchymal and histiocytic tumors. This review examines the cytohistological features of various nonepithelial and nonlymphoid tumors of the thyroid, including vascular lesions, neural tumors (including granular cell tumor and paraganglioma), smooth muscle tumors, solitary fibrous tumor, histiocytic neoplasms (eg, Langerhans cell histiocytosis and Rosai-Dorfman disease), and follicular dendritic cell sarcoma. Their differential diagnosis is discussed, including recommendations to prevent the pitfall of mistaking these rare tumors for more common epithelial thyroid neoplasms.

Primary Langerhans Cell Histiocytosis in Thyroid

Background

Langerhans cell histiocytosis (LCH) is a rare group of neoplastic diseases resulting from Langerhans dendritic cells. The most common site (80%) is bones. Thyroid gland involvement is exceedingly rare and usually expected to be seen as a part of multisystemic disease.

Case Report

We present a 45 year old male patient operated due to multinodular goiter and neck pain, and diagnosed with LCH in his postoperative pathologic examination. As a result of the systemic screening performed after the pathological diagnosis, the disease was interestingly localized to the thyroid gland. Systemic involvement did not develop in the two-year follow-up of the patient who did not receive additional chemotherapy treatment.

Conclusion

It is difficult to diagnose LCH in the thyroid gland before surgery. Although surgical treatment with or without chemotherapy is recommended, surgery is not recommended alone since it is generally systemic involvement. However, in primary thyroid LCH cases limited to the thyroid gland, we recommend that only total thyroidectomy treatment should be kept in mind.

Langerhans' Cell Histiocytosis Masquerading as Metastatic Papillary Thyroid Cancer on F-18 FDG PET/CT: Diagnostic Dilemma Solved by PET/CT-Guided Biopsy

We present a case of papillary thyroid cancer (post-thyroidectomy status) on regular treatment with suppressive Levothyroxine therapy. On follow-up at 6 months after radioactive iodine ablation for remnant thyroid tissue, her thyroglobulin, and anti-thyroglobulin levels were 0.06 ng/ml and 670 IU/ml, respectively. Low-dose whole-body I-131 scan was negative. To look for the cause of isolated increased anti-thyroglobulin level, a whole-body ¹⁸F-FDG PET/CT was done which revealed multiple FDG-avid lytic skeletal lesions suggestive of metastases. For confirmation of diagnosis, ¹⁸F-FDG PET/CT-guided metabolic biopsy was done, which revealed Langerhans' cell histiocytosis on histopathological examination.

Langerhans cell histiocytosis of the thyroid complicated by papillary thyroid carcinoma: A case report and brief literature review

RATIONALE

Langerhans cell histiocytosis (LCH) involves mainly the skin and bone and rarely the thyroid. Meanwhile, papillary thyroid carcinoma (PTC) is the most common subtype of thyroid cancer. Both LCH and PTC could make the thyroid enlarged and hypermetabolic. The coincidence of these 2 events in a patient is rare, and this paper aimed to report such case.

PATIENT CONCERNS

A 40-year-old man presented with polyuria and polydipsia for 5 years. The symptoms had been relieved well by drug therapy for >4 years, until the drugs could not control the symptoms anymore and an extensively enlarged thyroid gland was noticed.

DIAGNOSES

Thyroid ultrasound showed a nodule with microcalcification in the upper right lobe, positron emission tomography/computer tomography scan demonstrated thyroid hypermetabolism, and fine needle aspiration (FNA) revealed PTC. Right lobectomy of the thyroid and cervical lymph node biopsy verified the diagnosis "LCH of the thyroid complicated by PTC."

INTERVENTIONS

The ultrasound-guided FNA biopsy was performed prior to right lobectomy of the thyroid and cervical lymph node biopsy. Postoperative histopathological examination confirmed the diagnosis, after which the patient received adjuvant chemotherapy.

OUTCOMES

After 5 cycles of adjuvant chemotherapy, the patient had been followed up for 2 years. LCH was controlled satisfactorily and there was no significant sign of recurrence or metastasis of PTC.

LESSONS

LCH of the thyroid complicated by PTC is rare. Thyroid involvement should always be considered in the differential diagnosis of LCH patients. Surgery for PTC followed by chemotherapy for LCH may be the suitable treatment.

An unusual case of adult-onset multi-systemic Langerhans cell histiocytosis with perianal and incident thyroid involvement

Summary

Langerhans cell histiocytosis (LCH) is a rare sporadic disease characterized by histiocytic neoplastic infiltration of various organ systems and a wide spectrum of clinical manifestations, ranging from benign and self-limiting to lethal. Herein, we report a rare case of adult-onset multi-systemic LCH in a 36-year-old male patient with an initial perianal presentation and incidental finding of subsequent thyroid gland involvement in the follow-up period. The patient with a history of perianal LCH treated with surgical excision and local radiotherapy was referred to our Endocrinology Department upon detection of hypermetabolic nodular lesions in the left lateral lobe of thyroid gland on positron emission tomography–computed tomography (PET/CT) scan in the nineth month of follow-up. Current evaluation revealed euthyroid status, a hypoechoic solid lesion of 13 × 9 mm in size with irregular borders in the left thyroid lobe on thyroid USG and cytologic assessment of thyroid nodule. The patient was diagnosed with suspected, oncocytic lesion, Hashimoto thyroiditis or LCH. The patient underwent total thyroidectomy and pathological assessment confirmed the diagnosis of Langerhans cell histiocytosis. Assessments in the sixth month of postoperative follow-up revealed euthyroid status with no thyroid tissue remnants or pathological lymph node on thyroid USG. In view of the multifocal lesions indicating multi-system disease, a systemic chemotherapy protocol with combination of prednisone (PRED) and vinblastine (VBL) has been planned by the hematology department.

Learning points:

Cytological Diagnostic Approach in 3 Cases of Langerhans Cell Histiocytosis Presenting Primarily as a Thyroid Mass

BACKGROUND

Langerhans cell histiocytosis (LCH) is a monoclonal disease of specialised histiocytes characterised by the proliferation of neoplastic Langerhans cells (LCs) with a varying admixture of mature lymphocytes, eosinophils and plasma cells. LCH commonly occurs in the paediatric population and young adults with the involvement of bone, skin and lymph nodes. LCH has a protracted clinical course with an overall mortality rate of 3%. Primary involvement of the thyroid gland in LCH at presentation is a rare phenomenon that can result in misdiagnosis with consequent mismanagement.

CASE

Ultrasound-guided fine-needle aspiration cytology (FNAC) of the thyroid was performed in 3 cases at a tertiary cancer centre, including 2 referral cases where the patient presented with the only symptom of progressive thyroid enlargement. These cases were reported initially or on review and the results were correlated with histology/ancillary techniques. A cytological diagnosis of suspicion for LCH was offered in 2 cases at our centre and 1 case was referred to our centre with a diagnosis of suspected papillary thyroid carcinoma. On review of outside smears at our centre, the diagnosis was changed to suspected LCH. The diagnosis was confirmed by immunopositivity for CD68, CD1a and S100 in 1 case and Tru-cut biopsy followed by immunohistochemistry for CD1a, S100, TTF-1 and LCA in the other 2 cases.

CONCLUSION

FNAC was helpful in accurately diagnosing LCH even though the presentation was unusual. Thus, unnecessary surgery was obviated.

Thyroid atypia of undetermined significance or follicular lesion of undetermined significance: an indispensable Bethesda 2010 diagnostic category or waste garbage?

OBJECTIVE

The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) was introduced in thyroid cytology in 2007 and is now generally accepted. BSRTC categories include a morphologic description and risk of malignancy as well as follow-up suggestions in each group. However, the category entitled 'atypia of undetermined significance or follicular lesion of undetermined significance' (AUS/FLUS) is problematic. This category is heterogeneous and has been overused so far.

STUDY DESIGN

Twenty-six studies were included in a meta-analysis. In addition to AUS/FLUS percentage, we analysed repeated AUS/FLUS percentage, cytological and histological correlations, and risk of malignancy and neoplasm for AUS/FLUS. Furthermore, stratification, inter- and intra-observer variability, and the possibility of a switch to another category and its clinical consequences were reviewed.

RESULTS

Out of a total of 81,833 cases, AUS/FLUS accounted for 10.9%, with a 34% risk of malignancy. Persistent AUS/FLUS was found in 21.6% in repeated cytology. Cytohistological correlation was analysed from 16 studies (4,964 cases), revealing 10.4% as AUS/FLUS and a 21.5% risk of malignancy.

CONCLUSIONS

An AUS/FLUS category seems to be currently reasonable with clearly defined cytomorphological criteria which do not correspond unequivocally with those of the other categories. An AUS/FLUS category is justified and possible means of its improvement with immunohistochemistry, molecular analysis and imaging are discussed.