Micronodular PEComas of the appendix.

AIMS: Perivascular epithelioid cell tumours (PEComas) of the appendix have been reported very rarely. In this study, we describe three cases of a distinctive micronodular proliferation in the appendix consistent with a variant of PEComa. Although known as 'granular degeneration of smooth muscle' in prior reports, we reappraise its clinicopathological, immunohistochemical and ultrastructural features which support a change in classification. METHODS AND RESULTS: Patients were two females (aged 33 and 41 years) and one male (aged 41). None had a history of tuberous sclerosis. Histologically, each case demonstrated a multifocal nodular proliferation towards the distal tip of the appendix, composed of epithelioid cells with abundant granular eosinophilic to clear cytoplasm. By immunohistochemistry, the lesional cells were positive for muscle markers [smooth muscle actin (SMA) and desmin], melanocytic markers (HMB45, melan A), cathepsin K and the lysosomal marker NKI-C3 in each case. MITF was positive in two of three cases. None expressed S100 protein. Electron microscopy in one case revealed striated electron-dense structures consistent with pre-melanosomes. Follow-up, available in one case, showed no recurrence at 5 years. CONCLUSIONS: We propose the term 'micronodular PEComa' for this appendiceal lesion to reflect more accurately its histological and immunohistochemical characteristics, which include consistent positivity for both muscle and melanocytic markers. Micronodular PEComa seems to follow an indolent course, consistent with its uniformly low-grade histological features, and appears to be unassociated with tuberous sclerosis.

Conjunctival nevi and melanoma: multiparametric immunohistochemical analysis, including p16, SOX10, HMB45, and Ki-67.

The role of p16 in the diagnosis and prognosis of conjunctival melanocytic lesions in the context of other clinical and immunohistochemical parameters has not been systematically explored. This study was conducted to determine whether p16 is a useful parameter in the diagnosis and prognosis of conjunctival melanocytic nevi and melanoma, either independently or as a component of immunohistochemical panels. Sixty-one patients underwent 61 biopsies for conjunctival melanocytic lesions between 2014 and 2018. Pathologic diagnoses were melanoma (n = 25, 41%), nevus (n = 21, 34%), and conjunctival melanocytic lesion of uncertain malignant potential (n = 15, 25%). The biopsies were assessed for expression of p16, SOX10, HMB45, and Ki-67. In a multivariable model, the parameters most predictive of melanoma versus nevus were diffuse HMB45 staining (odds ratio [OR] = 45, confidence interval [CI] = 4.4-457, P = .02] and p16 nuclear H-score≤115 (OR = 9.5, CI = 1.2-77; P = .04). There was no association of p16 expression with melanoma thickness. Next-generation sequencing identified no CDKN2A mutations or copy number alterations in 12 conjunctival melanomas, including the tumors with absent p16 expression. This study demonstrates that p16 immunohistochemical stain is useful in distinguishing conjunctival melanocytic nevi from melanoma, particularly in combination with HMB45. P16 expression does not appear to correlate with CDKN2A status and melanoma thickness.

A surgical case of primary perivascular epithelioid cell tumor of the heart.

BACKGROUND: We encountered an extremely rare case of perivascular epithelioid cell tumor (PEComa) of the heart. CASE REPORT: A 54-year-old woman was admitted to our hospital because a solid mass developing in the left atrioventricular groove by computed tomography scans of the chest. Histologic examination of the resected tumor revealed that the tumor had proliferating fusiform or spheroid cells with clear cytoplasm. Immunostaining showed positive results for α-smooth muscle actin, a myogenic marker, and human melanin black-45 (HMB-45), leading to a diagnosis of PEComa. The patient was discharged uneventfully, and there was no recurrence for the last thirteen years postoperatively. CONCLUSIONS: We experienced a surgical case of PEComa primarily occurring in the heart. Although no sign of a recurrence is observed to date, we consider it necessary to follow up the case carefully.

An Incidental Diagnosis of Microscopic Renal Angiomyolipoma Completely Excised on Renal Biopsy: A Case Report.

BACKGROUND Microscopic tumor foci have been detected incidentally on renal biopsy, including renal cell carcinoma and renomedullary interstitial cell tumor (medullary fibroma). A report is presented of a case of an incidental finding of microscopic renal angiomyolipoma that was diagnosed and completely excised on core needle biopsy. CASE REPORT A 44-year-old woman was referred to our hospital for evaluation of persistent mild proteinuria. Three years previously, she was diagnosed with Cushing's syndrome associated with a right adrenal cortical adenoma, which was successfully treated with unilateral adrenalectomy. At the time of surgery, abdominal computed tomography (CT) showed no renal lesions. During the present admission, a renal biopsy was performed that showed minimal changes in the renal glomeruli and interstitium. Immunofluorescence showed weakly positive staining for IgM in the glomeruli and no dense deposits. A microscopic focus of a predominantly spindle-cell tumor was found in the corticomedullary region. Immunohistochemistry showed positive immunostaining for HMB-45, Melan-A, and alpha-smooth muscle actin (ASMA), which supported a diagnosis of angiomyolipoma. Abdominal ultrasound at one-year follow-up showed no evidence of residual renal tumor. CONCLUSIONS To our knowledge, this is the first reported case of a completely excised incidental microscopic renal angiomyolipoma. This case demonstrated that even when imaging findings are normal, renal biopsy may detect microscopic foci of primary renal tumors.

PNL2: A Useful Adjunct Biomarker to HMB45 in the Diagnosis of Uterine Perivascular Epithelioid Cell Tumor (PEComa).

Perivascular epithelioid cell tumors (PEComa) are rare neoplasms characterized by co-expression of melanocytic and muscle markers. HMB45 and Melan-A are used to confirm a PEComa diagnosis; however, both are often focally expressed and sensitivity for Melan-A is low. PNL2 is a reliable biomarker for epithelioid melanoma and renal angiomyolipoma/PEComa. The objective of this study was to determine PNL2 utility in diagnosing uterine PEComas as well as distinguishing PEComas from uterine smooth muscle tumors (SMTs). Twenty-one uterine PEComas and 45 SMTs were analyzed for PNL2; a subset was also stained for HMB45, Melan-A, Cathepsin-K, Desmin, and h-Caldesmon. Cases were scored as negative (0), focal (<10% of tumor cells), or patchy to diffusely positive (>10% of tumor cells). PEComas were positive for PNL2, HMB45, and Melan-A in 86%, 100%, and 57% of cases, respectively. In PEComas, PNL2 was patchy to diffusely positive more frequently (10/18, 56%) than Melan-A (4/12, 33%). In contrast, 2 of 45 (4%) SMTs were focally PNL2 positive; HMB45 was focally positive in 4 SMTs (11%) and all were negative for Melan-A. Desmin and h-Caldesmon were positive in 90% and 57% of PEComas, and 91% and 82% of SMTs. Cathepsin-K was positive in 100% of PEComas and 93% of SMTs. PNL2 is a useful biomarker for the diagnosis of uterine PEComa, with comparable sensitivity and specificity to HMB45. In contrast, PNL2 stains more PEComas when compared with Melan-A. Cathepsin-K, Desmin, and h-Caldesmon are of little utility for distinguishing PEComas and SMTs; however, lack of Cathepsin-K argues against PEComa. These results suggest that PNL2 should be used in conjunction with HMB45 in the diagnosis of PEComa of the uterine corpus.

CYSLTR2-mutant Cutaneous Melanocytic Neoplasms Frequently Simulate "Pigmented Epithelioid Melanocytoma," Expanding the Morphologic Spectrum of Blue Tumors: A Clinicopathologic Study of 7 Cases.

Recurrent activating Gαq mutations in the spectrum of blue nevi have been well studied. However, the clinicopathologic characteristics of the recently described CYSLTR2-mutant and PLCB4-mutant blue nevi remain limited, owing to their rarity. Herein, we present 7 CYSLTR2-mutant melanocytic neoplasms, including 1 cellular blue nevus, 4 atypical cellular blue nevi, and 2 blue nevus-like melanomas. They occurred on the scalp, breast, flank, forearm, thigh, leg, and ankle of 3 male patients and 4 female patients, with a median age of 43 (25 to 81) years at diagnosis. Five exhibited an exophytic growth, and 6 were heavily pigmented. A fascicular arrangement of medium to large spindle melanocytes was seen in 6 cases, but epithelioid cytology was present in only 2 cases, one of them being focal. A junctional component was present in 3 cases. Immunoreactivity for HMB45 was diffusely present, except in 1 cellular blue nevus. BAP1 nuclear immunoexpression was lost in 1 melanoma case. A canonical CYSLTR2 L129Q hotspot mutation was present in all cases. Altogether, these histopathologic findings suggest that CYSLTR2-mutant melanocytic blue neoplasms frequently exhibit a heavily pigmented exophytic tumor with a silhouette resembling "pigmented epithelioid melanocytoma" rather than usual cellular blue nevus. Moreover, most of these tumors were not clinically recognized as blue nevi and not located in the classic topography of cellular blue nevus aside from the scalp. However, a fascicular arrangement of medium to large-sized spindled melanocytes, as well as a lack of epithelioid or nevoid melanocytes, could be potential diagnostic clues to morphologically distinguish CYSLTR2-mutant tumors from "pigmented epithelioid melanocytoma."

Utility of Multistep Protocols in the Analysis of Sentinel Lymph Nodes in Cutaneous Melanoma: An Assessment of 194 Cases.

CONTEXT.­: Currently, no universal protocol exists for the assessment of sentinel lymph nodes (SLNs) in cutaneous melanoma. Many institutions use a multistep approach with multiple hematoxylin-eosin (H&E) and immunohistochemical stains. However, this can be a costly and time- and resource-consuming task. OBJECTIVE.­: To assess the utility for multistep protocols in the analysis of melanoma SLNs by specifically evaluating the Calgary Laboratory Services (CLS) protocol (which consists of 3 H&E slides and 1 S100 protein, 1 HMB-45, and 1 Melan-A slide per melanoma SLN block) and to develop a more streamlined protocol. DESIGN.­: Histologic slides from SLN resections from 194 patients with diagnosed cutaneous melanoma were submitted to the CLS dermatopathology group. Tissue blocks were processed according to the CLS SLN protocol. The slides were re-reviewed to determine whether or not metastatic melanoma was identified microscopically at each step of the protocol. Using SPSS software, a decision tree was then created to determine which step most accurately reflected the true diagnosis. RESULTS.­: We found with Melan-A immunostain that 337 of 337 negative SLNs (100%) were correctly diagnosed as negative and 55 of 56 positive nodes (98.2%) were correctly diagnosed as positive. With the addition of an H&E level, 393 of 393 SLNs (100%) were accurately diagnosed. CONCLUSIONS.­: We recommend routine melanoma SLN evaluation protocols be limited to 2 slides: 1 H&E stain and 1 Melan-A stain. This protocol is both time- and cost-efficient and yields high diagnostic accuracy.

[Primitive myxoid melanoma: An unusual histological aspect]. / Mélanome myxoïde primitif : une forme histologique inhabituelle.

BACKGROUND: Myxoid melanoma is a rare variant of melanoma that must be recognised. Herein we describe a new metastatic case. PATIENTS AND METHODS: A 78-year-old woman consulted for a firm, pinkish nodule measuring 25mm and present for six months on her left leg. Analysis of the biopsy revealed achromic fusiform tumour cells separated by large myxoid plaques. Labeling of SOX10, HMB45 and PS100 was diffuse and of moderate to strong intensity. A diagnosis of myxoid melanoma was considered, with Breslow thickness of 9mm. Surgery was carried out with a 2-cm margin and confirmed the diagnosis. Dermatological follow-up at one year revealed metastatic spread to the ganglia, pleura, liver and bone. DISCUSSION: Few cases of primary myxoid melanoma have been described, and the condition is probably underdiagnosed. The classic clinical presentation of this condition consists of a solitary achromic nodule found chiefly on the limbs. The microscopic appearance is relatively non-specific. Immunohistochemical analysis may indicate melanocytic involvement: cells exhibit expression of SOX10, diffuse expression of protein S100, and less consistent and more variable expression of HMB45. The increasingly common use of anti-SOX10 is of value since it is expressed in the nucleus of melanocytes. Mastocytes and TGF-ß secretion appear to be involved in myxoid stroma production. In the absence of specific codification, management of myxoid melanoma is comparable to that of other types of melanoma. There is uncertainty about the prognosis, with the involvement of TGF-ß possibly indicating the aggressive potential of this type of tumour.

[Meningeal melanoma arising from a preexisting meningeal melanocytoma: A clinical, pathological and cytogenetic study about one case]. / Transformation d'un mélanocytome méningé en mélanome : étude clinique, histopathologique et cytogénétique.

Meningeal melanocytic tumors are rare. We report an exceptional case of transformation of a meningeal melanocytoma in a malignant melanoma. The course of the disease extents from 61-years to 85-years and ends with the death of the patient. Besides histopathological and immunohistochemical data, we also report the array CGH study of the melanocytoma and melanoma components suggesting the malignant transformation from whole chromosome gains in the melanocytoma to additional segmental aberrations in the malignant melanoma. Beyond the rarity of this tumor subtype, this case report highlights the potential interest of molecular analyses for diagnostic and prognostic purposes in the field of meningeal melanocytic tumors.

Traumatic Neuroma With Melanoma Perineural Invasion.

Traumatic neuroma is a reactive non-neoplastic neural proliferation that results from trauma. Although such type of lesions found surgical scars due to different reasons, its involvement by residual or recurrent malignancies is rarely reported. In this article, we describe an unusual case of traumatic neuroma with perineural invasion by invasive melanoma.

[Primary melanoma of the bladder. A case report]. / Melanoma primario de vejiga urinaria: presentación de caso.

Primary melanoma of the urinary bladder is rare. We report a case of a 58-year-old woman, who presented with a 4 month history of dysuria and hematuria. A biopsy indicated a diagnosis of invasive melanoma and a partial cystectomy was performed. The neoplasm had invaded the entire thickness of the bladder wall and the neoplastic cells were positive for Melan A and HMB-45. Four months later a urinary bladder measuring 13×7×5cm was sent for histopathology. Melanoma, melanosis and a melanocytic nevus were seen; the latter was confirmed by the positivity to melanocytic markers of non-atypical cells in both the urothelial basal layer and areas distant from the tumour. The patient died nine months later.

Sudden unexpected death with primary adrenal lymphoma.

An 82-year-old man was found dead on the road near his home with unwitnessed interval of 3 h from final witness. He had been diagnosed with hypertension and mild aortic stenosis (AS) 13 years before death, and was continuously followed up with medication. Although a recent medical check-up related to cardiac function was stable and consistent with moderate AS, he sometimes complained of general fatigue, anorexia associated with intermittent mild fever and rare vomiting in the weeks before death. At autopsy, no lethal injury or drug intoxication was found, but congenital bicuspid aortic valve (BAV) with central rache was found. Although calcification was found in a restricted area of one cusp, valvular structural deformity was clearly milder than in typical severe AS cases. Moderate left ventricular hypertrophy without coronary disease was found. A brownish-red, soft nodular lesion was found in both adrenal glands, but no other tumorous focus was evident in any other organs. Immunohistochemical examination showed that B-lymphocyte-derived markers (CD20, melanoma associated antigen (mutated) 1, and CD79a) were exclusively positive. Therefore, we diagnosed primary adrenal lymphoma (PAL), diffuse large B-cell lymphoma phenotype. We concluded that the cause of sudden unexpected death (SUD) was adrenal insufficiency associated with PAL, with a background of moderate AS related to BAV.

Melanotic Xp11 translocation renal cancer: a report of a distinctive case and a review of the literature.

BACKGROUND: Melanotic Xp11 translocation renal cancer (TRC) is a newly described exceedingly rare tumor, and its characterization remains controversial. This study aimed to describe a case of distinctive melanotic Xp11 TRC and to elucidate its clinicopathological and molecular genetic features. CASE PRESENTATION: A 44-year-old Chinese female presented with a left renal mass. Abdominal ultrasonography and computed tomography (CT) scans revealed a 4.5 cm × 4.0 cm mass in the left kidney. Grossly, the well-demarcated mass was black with moderately firm consistency. Microscopic examination indicated that the tumor was characterized by the presence of nests and cords of polygonal cells with clear and granular eosinophilic cytoplasm, central round to oval nuclei and occasional nucleoli. Intracytoplasmic melanin was observed in approximately 45% of tumor cells. Uniquely, the tumor presented with intranuclear eosinophilic pseudoinclusions and thick-walled stromal blood vessels. IHC showed that tumor cells were diffusely positive for TFE3 and exhibited patchy and weak HMB45 staining. FISH confirmed the presence of TFE3 rearrangement. CONCLUSION: This case is the twentieth published case of melanotic Xp11 TRC. Moreover, the present patient had a favorable prognosis given that she was disease free at her 113-month postoperative follow-up. Our case adds to the small body of literature on these exceptionally rare tumors and widens their clinicopathological spectrum.