Medullary thyroid carcinoma with ectopic adrenocorticotropic hormone syndrome

Endocrine Perspective of Cutaneous Lichen Amyloidosis: RET-C634 Pathogenic Variant in Multiple Endocrine Neoplasia Type 2

BACKGROUND

Medullary thyroid carcinoma (MTC), the third most frequent histological type of thyroid malignancy, may be found isolated or as part of multiple endocrine neoplasia type 2 (MEN2). One particular subtype of this autosomal dominant-transmitted syndrome includes an association with cutaneous lichen amyloidosis, although, generally, a tide genotype-phenotype correlation is described in patients who carry RET proto-oncogene pathogenic variants.

METHODS

Our objective was to provide an endocrine perspective of a case series diagnosed with RET-positive familial MTC associated with cutaneous primary lichen amyloidosis amid the confirmation of MEN2. Six members of the same family had cutaneous lesion with different features (from hyperpigmented, velvety to red/pink appearance) and four of them harbored a RET pathogenic variant at 634 codon (exon 11): c.1900T>G, p.634G (TGC634CGC).

RESULTS

All six patients were females with the lesion at the interscapular region. Except for two women, four of these subjects were investigated and had MTC (three of them with postoperatory confirmation). The youngest affected individual was 6 years old. The three adult females were confirmed with RET pathogenic variant during their 30s, while the girl underwent the familial screening as a newborn. None of them had primary hyperparathyroidism until the present time, except for one subject, and two out of the three adults also had bilateral pheochromocytoma. Notably, all patients were rather asymptomatic from the endocrine perspective at the moment when endocrine tumor/cancer was confirmed, and the skin was progressively affected a few years before the actual MEN2 confirmation.

CONCLUSIONS

This case series highlights the following key message: awareness of the dermatologic findings in MTC/MEN2 patients is essential since lesions such as cutaneous lichen amyloidosis might represent the skin signature of the endocrine condition even before the actual endocrine manifestations. These data add to the limited published reports with respect to this particular presentation, noting the fact that RET-C634 is the most frequent pathogenic variant in MEN2-associated lichen amyloidosis; females are more often affected; the interscapular region is the preferred site; the age of diagnosis might be within the third decade of life, while we reported one of the youngest patients with the lesion. The same RET pathogenic variant is not associated with the same dermatologic features as shown in the vignette. The same RET mutation does not mean that all family members will present the same skin anomaly.

Medullary Thyroid Cancer with Ectopic Cushing's Syndrome: A Case Report and Systematic Review of Detailed Cases from the Literature

Background: Medullary thyroid cancer (MTC) is a neuroendocrine tumor arising from parafollicular C-cells of the thyroid gland that, in rare cases, can cause a paraneoplastic ectopic Cushing's syndrome (ECS). The development of Cushing's syndrome (CS) in MTC patients is generally associated with advanced disease and poor prognosis. Summary: We described a case of severe CS due to MTC in a young male. We performed a systematic review to identify cases of ECS due to MTC. We searched PubMed, Scopus, and Web of Science for publications between database inception and February 2022 and we collected the patient characteristics, disease presentation, employed treatment strategies, and disease outcomes. In addition to our patient, we identified 96 cases of ECS due to MTC reported in literature. Mean age at diagnosis was 44.4 years (range 10-84), and there was a male predominance (male:female [M:F] = 1.8:1). Most patients (51%) presented with metastatic disease at diagnosis and showed severe hypercortisolism. Seventeen patients developed distant metastasis and hypercortisolism during follow-up. Interestingly, in 48% of patients, the diagnosis of CS followed the diagnosis of MTC with a median time of 48 months but, among patients in whom the diagnosis was concomitant (38%), symptoms due to hypercortisolism were frequently the reason for seeking medical advice. Pathology results showed evidence of adrenocorticotropic hormone (ACTH) or corticotropin releasing hormone (CRH) positive cells in 76% of patients in whom they were tested. The management of hypercortisolism was challenging in most patients with 48% requiring, eventually, definitive treatment with bilateral adrenalectomy (BLA). Recently, some limited evidence has emerged regarding tyrosine kinase inhibitors (TKIs) treatment for hypercortisolism in patients with ECS due to MTC. Despite limited information on survival, prognosis was generally poor and the main causes of death were either complications of CS or disease progression. Conclusions: Despite its rarity, MTC should be considered in the differential diagnosis of ECS. Management of hypercortisolism is a key factor to improve the patient's symptoms but it is often challenging and BLA is frequently required. Further studies are needed for investigating the role of TKIs in patients with MTC with ECS.