Intraoperativer Gefrierschnitt der Schilddrüse

Sporadic noninvasive medullary thyroid neoplasm: A desmoplasia-negative unifocal nonmetastatic tumor cured by hemithyroidectomy

BACKGROUND

The absence of primary tumor desmoplasia, a marker of node metastases, on frozen section may help reduce the extent of surgery without compromising the biochemical cure. We aimed to clarify whether hemithyroidectomy with diagnostic ipsilateral central neck dissection can replace total thyroidectomy with routine central neck dissection in patients with sporadic medullary thyroid cancer.

METHODS

We retrospectively evaluated data collected from patients who had undergone primary neck surgery for hypercalcitoninemic sporadic medullary thyroid cancer between January 2017 and December 2022 at one institution.

RESULTS

Of the 25 patients we examined, 19 had desmoplasia-negative and 6 desmoplasia-positive primary thyroid tumors on frozen section. The desmoplasia-negative patients had undergone less surgery with fewer nodes removed than the desmoplasia-positive patients (medians of 6 vs 31 nodes, P < .001). The desmoplasia-negative patients had predominantly undergone hemithyroidectomy with ipsilateral central neck dissection. None of the desmoplasia-negative tumors was multifocal (0 of 19 desmoplasia-negative vs 2 of 6 desmoplasia-positive or 0% vs 33%, P = .050) or node-positive (0 of 19 vs 6 of 6 patients or 0% vs 100%; medians of 0 vs 3.5 node metastases; both P < .001). Despite limited surgery, all desmoplasia-negative patients attained and maintained biochemical cure.

CONCLUSION

Hemithyroidectomy combined with diagnostic ipsilateral central neck dissection is a viable risk-reducing and curative strategy for desmoplasia-negative and node-negative, nonmetastatic unifocal tumors, for which we propose the term sporadic noninvasive medullary thyroid neoplasm (SNMTP).

[Hemithyroidectomy or total thyroidectomy for low-risk papillary thyroid cancer? : Surgical criteria for primary and secondary choice of treatment in an interdisciplinary treatment concept]

The increase in small intrathyroid papillary thyroid cancer (PTC) observed worldwide over the past two decades, with no increase in cancer-specific mortality, has challenged the previous concept of total thyroidectomy as a one-size-fits-all panacea. After exclusion of papillary microcarcinomas, a systematic review of 20 clinical studies published since 2002, which compared hemithyroidectomy (HT) to total thyroidectomy (TT), found comparable long-term oncological outcomes for low-risk papillary thyroid cancer (LRPTC) 1-4 cm in diameter, whereas postoperative complication rates were markedly lower for HT. To refine individual treatment plans, HT should be combined with ipsilateral central lymph node dissection and intraoperative frozen section analysis for staging. Based on recent evidence from studies and in consideration of individual risk factors, patients with LRPTC can be offered the concept of HT as an alternative to the standard TT. A prerequisite for the treatment selection and decision is a comprehensive patient clarification of the possible advantages and disadvantages of both approaches.

Abandoning node dissection for desmoplasia-negative encapsulated unifocal sporadic medullary thyroid cancer

BACKGROUND

Predictive criteria to determine the absence of node metastases from thyroid specimens are scarce for sporadic medullary thyroid cancer.

METHODS

Histopathologic stratification of patients with unifocal sporadic medullary thyroid cancer ≤25 mm with ≥10 neck nodes at thyroidectomy to evaluate the suitability of desmoplasia (7 increments) and tumor capsule integrity (5 decrements) for intraoperative prediction of node metastasis in unifocal sporadic medullary thyroid cancer.

RESULTS

Paraffin-embedded thyroid specimens were available for 139 eligible patients. Significant (P < .001) associations were found between increasing desmoplasia and decreasing tumor capsule integrity and nodal disease (from 0 to 79% and 0 to 62%); the number of node metastases (medians, from 0 to 3 and 0 to 2 nodes); and biochemical cure (from 100 to 36% and 100 to 58%). Desmoplasia (low-moderate to high, with fibrosis >10%) and breach of the tumor capsule (>3 extensions; 1 extension >3 mm in width; or diffuse growth without tumor capsule) yielded excellent sensitivity and negative predictive value (100%), with moderate specificity (57 and 48%) and positive predictive value (50 and 46%). In retrospect, node dissection proved unnecessary in 55 (57%) and 47 (48%) patients who harbored desmoplasia-negative and encapsulated tumors. When available frozen sections were histopathologically compared with matching paraffin-embedded thyroid tumor specimens, concordance was 98% (53 of 54 pairs): 1 of 7 upgrades changed the diagnosis to desmoplasia, whereas 1 of 3 downgrades shifted the diagnosis of tumor capsule breach from "present" to "absent."

CONCLUSIONS

Patients with desmoplasia-negative encapsulated sporadic medullary thyroid cancer may forgo node dissection at specialist centers.

[Diagnostic principles of thyroid tumors in pathology : Relevant changes due to the current WHO classification]

The current edition of the WHO classification of thyroid tumors (2017) contains a number of very relevant changes with considerable consequences for the diagnostic assessment of thyroid specimens. This applies to both the histomorphological examination of surgical specimens and the preoperative fine needle biopsy (FNB). In addition, molecular pathological examinations are becoming increasingly important in the diagnosis of thyroid tumors. Changes affect practically all areas of thyroid tumor diagnostics. Some of these changes have far-reaching consequences that justify a comprehensive commentary and query of the knowledge acquired in the form of this CME article.

[Pathology and molecular profile of differentiated thyroid carcinoma]

The clinical term of differentiated thyroid carcinoma (DTC) includes follicular (FTC) and papillary thyroid carcinomas (PTC). In diagnostic thyroid pathology, however, the term differentiated carcinoma (NOS) is used only very rarely for tumors with morphological features of both FTC and PTC. The current World Health Organization (WHO) classification of thyroid tumors introduced the entity of non-invasive follicular thyroid neoplasm with papillary-like nuclear features (NIFTP). As a result, the diagnostic criteria for PTC had to be adjusted (compulsory histological demonstration of invasion and/or papillae), which also significantly limited the diagnostic potential of a fine needle biopsy (FNB) of the thyroid. The FTC is now divided into three distinct subgroups. Moreover, the WHO classification also established the diagnostic criteria of poorly differentiated thyroid carcinoma (PDTC), which has to be distinguished from both differentiated carcinomas and benign adenomas. This article also summarizes the current diagnostic status of molecular pathological analyses of thyroid tumors.

[Extent of resection in intrathyroidal medullary thyroid cancer]

Improvements in preoperative diagnostic modalities in conjunction with highly sensitive calcitonin assays, ultrasound and functional imaging modalities and differentiated genetic testing for detection of hereditary forms, have enabled detection and resection of medullary thyroid carcinoma at an increasingly earlier stage. These developments open up possibilities to deescalate primary surgery adapted to these stages and avoid surgical overtreatment in locally limited tumor growth: thus, promoting a shift from routinely recommended total thyroidectomy with bilateral central lymph node dissection in favor of limited unilateral thyroid resection. Prerequisites for limited thyroid resection include clinical evidence that the tumor is sporadic, unifocal and confined to the thyroid. Corresponding calcitonin levels should also indicate that a biochemical cure will be achieved after unilateral resection. A decisive structural prerequisite for such a limited concept is the low threshold availability of intraoperative frozen section analysis that reliably detects and evaluates a medullary thyroid carcinoma and can assess a breach of the thyroid capsule and desmoplasia with certainty.

[Inflammatory diseases of the thyroid gland]

This review article deals with the classification, clinical features and morphology of thyroiditis. These inflammatory diseases account for approximately 20 % of all thyroid diseases. The vast majority of cases of thyroiditis are of immunogenic origin while non-immunogenic thyroiditis (caused by pathogens or iatrogenic) is a rarity.