Cutaneous myxomas and a psammomatous melanotic schwannoma in a patient with Carney complex

The "Pigmented Side" of Nerve Sheaths: Malignant Melanotic Nerve Sheath Tumor

Malignant melanotic nerve sheath tumor (MMNST) represents a highly aggressive neoplasm arising both in peripheral and cranial nerves. It accounts for < 1% of all nerve sheath tumors, but the real incidence may not be well defined yet because of the evolution of its nomenclature. To date, it is considered a distinct tumor type, no longer as the pigmented variant of schwannoma, with a different clinical course and biological behavior. MMNSTs exhibit a specific genetic hallmark related to the PRKAR1A gene, which explains the major incidence in Carney Complex-affected patients. One of the more frequent localizations is the paravertebral region, where it poses diagnostic concerns with both primary tumors arising from soft tissues and the meningeal covering, as well as metastatic ones (ie, melanoma). Herein we present a patient with an MMNST accompanied by the main clinical, radiological, histopathological, and molecular findings, stressing the need for a multidisciplinary diagnostic approach. To the best of our knowledge, this is the first report of proton beam therapy for MMNST. We also performed a literature review to collect and compare the more recent data in English literature and to highlight the "keep-in-mind" concepts to apply in a multidisciplinary diagnostic algorithm, with a focus on histopathology and related pitfalls.

Novel PRKAR1A mutation in Carney complex: a case report and literature review

Objective

Carney complex is a rare autosomal dominant syndrome that has been shown to be associated with inactivation due to PRKAR1A mutations. We revealed a novel PRKAR1A gene mutation in Chinese patient with Carney complex and review the literature to enhance understanding of Carney complex.

Case presentation

A 23-year-old Chinese male patient with a family history cardiac myxoma was admitted to our Department of Endocrinology because of central obesity and hyperpigmentation. Physical examination revealed a maximum blood pressure of 150/93mmHg, a waist circumference of 102cm, a weight of 70kg, a height of 170cm, and a BMI of 24.22kg/m2. Additionally, there was spotty skin pigmentation on the lip mucosa, purple striae on the abdomen, thin skin on both legs, and visible veins. Blood examination revealed hypercortisolemia, decreased adrenocorticotropic hormone (ACTH) levels and failure to suppress cortisol with low and high-dose dexamethasone suppression tests. Magnetic resonance imaging (MRI) scan revealed multiple small adrenal nodules and Retroperitoneal neurogenic tumor. Genetic testing showed a novel heterozygous mutation in exon 5 of PRKAR1A (c.500_502 + 8delAAGGTAAGGGC). The patient underwent resection of the right adrenal gland and retroperitoneal neoplasms in 2020. Postoperative pathology following the right adrenal gland resection showed nodular hyperplasia of the adrenal cortex. The pathology from the retroperitoneal tumor resection revealed spindle cell tumors rich in pigment and cells. The patient was diagnosed as Carney complex according to Stratakis CA in 2001 guidelines. After long-term follow-up, the patient's condition was stable, with weight loss, waist circumference reduction, significantly lower cortisol levels, and normal blood lipids.

Conclusion

This case reported a Carney complex in a Chinese patient, characterized clinically by non-ACTH-dependent Cushing's syndrome, familial recurrent cardiac myxomas, psammomatous melanotic schwannoma (PMS) and skin and mucosal pigmentation. A novel subtype of PRKAR1A mutation was discovered, which may affect the characteristics of the PRKAR1A protein and contribute to the development of Carney complex.

Case Report: Cutaneous melanocytic schwannoma with concomitant melanocytoma in a canine

Schwannoma is a nerve sheath tumour arising from differentiated Schwann cells, and melanocytic schwannoma (MS) is a rare variant where the Schwan cells produce melanin pigment. MS is typically associated with spinal nerve roots and there have been only ~20 reports of cutaneous or subcutaneous MS to-date in humans. In canines, there have only been two reports of MS, both associated with spinal root nerves. In this report, we describe a 7-year-old Weimaraner cross breed dog that presented with two pigmented lesions on the eyelids. The lesions were surgically removed and histological analysis revealed well-circumscribed, non-encapsulated, expansile, neoplasms that were displacing most of the dermis and adnexa. The first lesion was composed of spindloid cells arranged in short interlacing streams with large amounts of pale eosinophilic cytoplasm that sometimes contained fine melanin granules. In areas there were spindle cells arranged in verocay bodies which led to a diagnosis of MS. In contrast, the second lesion was composed of polygonal cells arranged in thick sheets with large amounts of pale eosinophilic cytoplasm that sometimes contained fine melanin granules. The diagnosis was melanocytoma (which is one of the macroscopic differential diagnoses for MS). Whilst melanocytoma is a commonly occurring cutaneous lesion in canines and surgical removal is considered curative, due to little being known about MS in dogs, the outcome remained guarded, as MS in humans has an unpredictable nature, and recurrence and metastasis have been reported.

Dermatological and endocrine elements in Carney complex (Review)

Carney complex (CΝC) is a very rare, autosomal dominant, hereditary syndrome. Seventy percent of individuals with CNC have germline inactivating or deleting mutations of the CNC1 gene [currently known as protein kinase cAMP-dependent type I regulatory subunit α (PRKAR1A), located at the 17q22-24 chromosome level], with 30% of cases presenting with phosphodiesterase gene mutations. A member of the lentiginosis family, dermatological features include: skin pigmentation, cutaneous/mucosal myxomas, usually diagnosed by the age of 20 years (neonatal presentation is exceptional, requiring a meticulous differential diagnosis). Melanocyte-derived tumors such as epithelioid blue nevi (with different levels of pigmentation) and pigmented epithelioid melanocytoma (previously 'animal-type melanoma') are often found. Myxomas, mesenchymal tumors with mostly a benign pattern, may be recurrent. Primary cutaneous melanotic schwannoma are atypical, while non-skin sites are frequent. Corticotropinomas or somatotropinomas are part of the hereditary syndrome-related pituitary adenomas (representing 5% of all). Primary pigmented nodular adrenocortical disease involves bilateral cortical hyperplasia causing Cushing syndrome (CS) at an earlier age than non-CNC cases; osteoporotic fractures seem more prevalent compare to CS of other etiologies. Typically benign, a few cases of adrenocortical carcinoma have been identified. A total of 5% of familial non-medullary thyroid cancer is syndromic, also including CNC. CNC-related thyroid frame includes: hyperthyroidism, follicular hyperplasia/adenomas, follicular carcinoma (usually aggressive, bilateral or multifocal). Large cell calcifying Sertoli cell tumors of the testes have malignant behavior in adults; in children these may induce precocious puberty. Two particular mammary tumors are found: myxoid fibroadenomas and breast myxomatosis. Cutaneous/subcutaneous lesions, pigmented or not, or any focal swelling of non-identified cause needs careful examination, since dermatological elements are among the earliest and most discernable by which to detect lesions in CNC, a systemic condition with multi-level endocrine involvement.

Melanotic Schwannoma of the Vulva: A Case Report and Review of the Literature

Melanotic schwannoma is a pigmented tumor of peripheral nerve differentiation. Primary cutaneous presentations are extremely rare, as the bulk of melanotic schwannomas tend to develop in paraspinal and axial sites. Tumors arise sporadically and in the setting of the Carney complex. Alterations in the gene encoding protein kinase A regulatory subunit-α (PRKAR1A) underlie most patients with the Carney complex and mediate melanotic schwannoma tumorigenesis. Melanotic schwannomas from noncutaneous sites can locally recur and metastasize widely, leading to a recent proposal to change the nomenclature to "malignant melanotic schwannian tumor." However, the clinicopathologic features of primary cutaneous melanotic schwannomas are relatively unexplored. We present a case of a nodule arising on the vulva of a 34-year-old woman. Microscopically, a dermal-based, heavily pigmented proliferation of plump spindled and epithelioid cells arrayed in nodules and fascicles was seen. Lesional cells stained positively for S100, Melan-A, and BAP1 but were negative for Prkar1α. Next-generation sequencing of a panel of 480 cancer-associated genes revealed that the tumor harbored a PRKAR1A p.S299fs truncating mutation and copy neutral loss of heterozygosity of chromosome 17q, the locus at which PRKAR1A resides. Importantly, no other genetic abnormalities or chromosomal copy number changes were identified. On the basis of combined histopathologic, immunohistochemical, and genetic features, a diagnosis of melanotic schwannoma was rendered. Overall, we present the first clinicopathologic description of a vulvar melanotic schwannoma, review the literature concerning cutaneous presentations of melanotic schwannoma, and propose that melanotic schwannian tumors native to skin may behave more indolently than their noncutaneous counterparts.