The varied presentation of metastatic melanoma in fine needle aspiration cytology of the breast

Aspiration cytology of liver abscess uncovering metastatic rectal mucosal melanoma-A case report

Aspirates of liver abscess are frequently encountered in routine practice and are often of a low index of suspicion. However, necrotic liver metastasis clinically and radiologically mimics liver abscesses, and malignant cells can be obscured in an inflammation-rich background on cytology. It is important to recognise malignant neoplasms in this scenario, in particular uncommon conditions such as metastatic mucosal melanoma.

Cytologic Findings in Serous Effusion Specimens from Melanoma Patients

INTRODUCTION

Metastatic melanoma (MM) is an uncommon finding in serous effusion specimens with a highly variable cytomorphology.

METHODS

We reviewed specimens submitted over a 19-year period to determine (a) the range of cytologic findings in effusion specimens from melanoma patients and (b) the cytologic presentation and immunoprofile of MM in effusion specimens.

RESULTS

Of 123 serous effusion specimens from patients with clinical notes of melanoma, 59% were reported negative for malignancy, 16% were reported with a non-melanoma malignancy, 19% MM, and 6% atypical, MM not excluded. Pleural fluids were twice as likely to be reported as MM than peritoneal samples. Review of 44 cases with confirmed MM showed the most common cytologic pattern was epithelioid. Most (88%) cases contained mainly dispersed plasmacytoid cells, but many (61%) also contained malignant cells arranged in loose groups. Rare cases also had spindle cells, giant bizarre cells, small lymphoid-like cells, or cells with large hard-edged vacuoles, mimicking other metastatic malignancies. MM cases containing predominantly plasmacytoid cells often mimicked reactive mesothelial cells. As well as being composed of cells of similar size, features such as bi- and multinucleation, round nuclei, mild anisokaryosis, nucleoli, and loose groups were common to both. Features seen more commonly in MM than reactive cells included large nucleoli (95%) and intranuclear cytoplasmic inclusions (41%), binucleate "bug-eyed demons," and small punctate vacuoles on the air-dried preparations. Pigment was identified in 36% of cases. Immunohistochemistry (IHC) is a valuable aid in confirming the cell type. The sensitivity for the most commonly used melanoma markers was as follows: S100 84% (21/25), pan-melanoma 100% (19/19), HMB45 92% (11/12), Melan A 92% (11/12), SOX10 91% (10/11). No staining was reported for calretinin (0/21), AE1/AE3 (0/11), EMA (0/16), Ber-Ep4 (0/13).

DISCUSSION

Effusion specimens from patients with a history of melanoma are frequently (40%) malignant but almost as likely to be reported as a nonmelanoma malignancy as MM. The cytology of MM may mimic a wide range of other metastatic malignancies but also often closely resembles reactive mesothelial cells. It is important to be aware of this latter pattern so that IHC markers can be applied.

Metastatic melanoma and rare melanoma variants: a review

The histopathological diagnosis of melanoma is fraught with potential pitfalls. In the setting of cutaneous metastatic melanoma, it is important to recognise the various histological patterns that can be encountered from the more common to the rare, including epidermotropic, folliculotropic, naevoid, and blue naevus-like. In addition, melanoma is notorious for phenotypic plasticity. Thus, there are many different subtypes and cytomorphological variations that can be difficult to recognise as melanoma, particularly in the recurrent or metastatic setting. Select melanoma variants including primary dermal, clear cell, plasmacytoid, signet ring cell, small cell, myxoid, rhabdoid, and dedifferentiated melanoma will be discussed, in addition to composite melanocytic neoplasms. This review is intended to remind the practitioner of key concepts of metastatic disease and select rare melanoma variants, while providing practical guidelines for accurate diagnosis.

Immunohistochemistry Applied to Breast Cytological Material

Fine-needle aspiration biopsies (FNABs) of the breast are minimally invasive procedures enabling the diagnosis of suspicious breast lesions. Unfortunately, they are often perceived as inferior to core-needle biopsies, namely because they are supposedly unable to differentiate between high-grade ductal carcinoma in situ and invasive carcinoma or provide material for ancillary testing. Several studies have shown, however, that FNAB samples, when handled properly, are indeed capable of providing sufficient and adequate material for ancillary testing, namely immunocytochemistry (ICC). We reviewed the published literature regarding the use of ICC for both diagnostic and theranostic uses in the different types of cytological samples obtained from FNABs of the breast, including smears, liquid-based cytology samples, and cellblocks. We found that p63 and 34βE12 show promise in aiding in the differential diagnosis between in situ and invasive lesions and that most other diagnostic markers may be used as in tissue. Regarding theranostic ICC markers, results vary between publications, but with care, these can successfully be performed in cytological samples. Air-dried smears should be avoided, and cellblocks are overall more versatile than cytology slides, enabling the evaluation of not only hormonal receptors and HER2 by ICC, but also of Ki-67. Particular attention should be paid to fixation and antigen retrieval procedures in all cases. We recommend that laboratories without experience perform short validation runs before adopting these techniques into clinical practice.

Malignant melanoma of the breast: controversies in the diagnosis and therapeutic management of a rare nosologic entity

Melanoma of the breast is an infrequent entity, presenting as either primary or metastatic from extramammary solid neoplasms. Depending on the involvement of the skin, primary malignant melanoma of the breast (PMMB) can be classified as cutaneous or noncutaneous. Cutaneous PMMB accounts for <5% of all melanomas and only 0.5% of all breast cancers. Furthermore, despite the rarity of metastatic breast neoplasms, melanoma comprises a frequent source of metastases. Metastatic potential of melanoma is associated with poor prognosis, and the majority of patients present more than one metastatic foci at the time of diagnosis. Diagnostic approach for both primary and metastatic melanomas of the breast is substantiated by fine needle aspiration (FNA) cytology along with immunohistochemistry. Nevertheless, verification of a metastatic mammary melanoma requires the discovery of a primary lesion. The mainstay of treatment for primary tumors is surgery, with radical local excision and axillary lymph node dissection or, on occasion, axillary sentinel node resection, while for metastatic tumors it depends on the specificities of the melanoma. Adjuvant therapy is always implemented. The aim of this survey is to meticulously review the literature of primary and metastatic malignant melanomas of the breast and report epidemiologic and clinicopathologic data for this rare entity. Clinical features, histogenesis, morphological, and immunochemical findings are discussed, while the role of current diagnostic and therapeutic management of this uncommon entity is emphasized.

Uncommon Histopathological Variants of Malignant Melanoma. Part 2

Despite new horizons opened by recent advances in molecular pathology, histological evaluation still remains the diagnostic gold standard regarding cutaneous melanocytic neoplasms. Several histological variants of melanoma have been described, and their knowledge is crucial for accurate diagnosis and classification of cases with unusual clinico-pathological features. Uncommon histological variants of melanoma have been described based on a broad constellation of features, including architectural pattern, stromal alterations, cytological attributes, and other morphological properties. This review is aimed at providing an extensive discussion of unusual but distinctive histopathological variants of melanoma.

Metastatic Melanoma With Papillary Features: A Mimic and Possible Diagnostic Pitfall

Papillary and pseudopapillary features are histopathologic findings typically associated with carcinomas (thyroid, pancreas, breast, prostate, bladder, kidney, or ovary) or mesothelioma. Melanoma is typically composed of nested and variably pigmented atypical cells. Here, we report a case of in-transit metastasis of melanoma presenting with prominent papillary features, and we discuss the differential diagnoses of neoplasms with papillary features. This case report suggests that the spectrum of neoplasms with papillary features should be expanded to include melanoma, a pattern that, to the best of our knowledge, is uncommon.

Fine-needle aspiration of metastatic melanoma presenting as bilateral breast cysts

Melanoma is the second most common non-hematopoietic malignancy after carcinomas to metastasize to the breast and often appears as a well-circumscribed, dense nodule on imaging. Although metastatic lesions presenting as bilateral cysts have been reported, this presentation is not common and may mimic benign breast cysts. We present a challenging case of metastatic melanoma presenting as bilateral breast cysts with spindled cytomorphology in a patient with a history of mammary carcinoma. Discordance between the spindled cytomorphology and the morphology of the core biopsy, which was similar to the patient's primary breast cancer, allowed for entertainment of other tumors and disease processes. Confirmatory immunostaining of the cytology material with HMB-45 was important to establish the diagnosis of metastatic melanoma. Diagn. Cytopathol. 2017;45:446-451. © 2017 Wiley Periodicals, Inc.

Amelanotic Melanoma Presenting with Plasmacytoid Morphology and BRAF V600 Mutation

Plasmacytoid melanoma is an unusual variant of malignant melanoma. The plasmacytoid morphology can be found in a variety of other malignancies including carcinomas, plasma cell neoplasms, lymphoproliferative disorders, and sarcomas. The authors report a rare case of plasmacytoid amelanotic malignant melanoma in a 78-year-old man presenting with an enlarging palpable, erythematous mass on his left posterior shoulder. A fine needle aspirate showed atypical findings with single amelanotic cells with high nuclear to cytoplasmic ratio, mono- and multi-nucleation with prominent nucleoli and intranuclear inclusions. Review of the excision and immunohistochemical analysis revealed the malignant plasmacytoid cells stained with vimentin, S-100, HMB-45, and other staining patterns consistent with melanoma. Initial evaluation was negative for other sites of disease. However, 4 months later, the patient was noted to have metastatic disease to his lungs and liver. Given that the tumor was noted to be BRAF V600R mutated, the patient was started on single agent dabrafenib. The plasmacytoid morphology can be found in a variety of malignancies. Melanoma should be considered in the differential diagnosis of any malignancy presenting with plasmacytoid features.

Cercariform cells: another cytologic feature distinguishing solid pseudopapillary neoplasms from pancreatic endocrine neoplasms and acinar cell carcinomas in endoscopic ultrasound-guided fine-needle aspirates

BACKGROUND

Solid pseudopapillary neoplasm (SPPN) is a rare tumor of unknown origin that occurs predominantly in the body or tail of the pancreas in young women. The authors recently identified cercariform (Greek: tailed) cells, similar to those described in urothelial carcinomas, as a consistent cytologic feature in ultrasound-guided fine-needle aspiration (EUS-FNA) samples from SPPNs. The objective of the current multi-institutional study was to define the value of these cells in the differential diagnosis of SPPN with other neoplasms characterized cytologically by the presence of monotonous, uniform cells in pancreatic aspirates: pancreatic neuroendocrine tumors (Pan-NETs) and acinar cell carcinomas (ACCs).

METHODS

The files of 4 academic hospitals were searched for SPPNs, Pan-NETs, and ACCs that were diagnosed by EUS-FNA. The slides were reviewed, and several cytologic features were recorded semiquantitatively to identify discriminating features between SPPNs, Pan-NETs, and ACCs.

RESULTS

From the analysis of 18 SPPNs, 4 ACCs, and 20 Pan-NETs, the following cytologic features were identified as common to all 3 neoplasms: single cells and rosettes/acinar cell groups, round-to-plasmacytoid cells, pale-to-granular cytoplasm, fine vacuoles, and binucleated cells. Papillary structures, cercariform cells, large cytoplasmic vacuoles, reniform nuclei, hyaline globules/magenta-colored material, and degenerative features (cholesterol crystals, calcifications, foam cells, or giant cells) were significantly more common in SPPNs. Prominent nuclear grooves were encountered in only 4 of 18 SPPNs.

CONCLUSIONS

The current results indicated that the presence of cercariform cells is another useful clue for the cytologic diagnosis of SPPN in challenging cases.