Balloon cell malignant melanoma

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.

Balloon Cell Melanoma: Presentation of Four Cases with a Comprehensive Review of the Literature

BACKGROUND

balloon cell melanoma represents less than 1% of all histological forms of malignant melanoma and represents a diagnostic challenge for the dermatopathologist.

METHODS

in this paper we present our cases of BCM found in our daily practice from 1 January 2008 to 31 December 2021, and we conduct a review of the literature relating to this entity in the period from the first description, 1970, to early 2022.

RESULTS

four cases of melanoma balloon cell have been extrapolated from our electronic database, while in the review of the literature we have identified 115 cases of patients with primary and/or metastatic BCM.

CONCLUSIONS

we believe that future studies with numerous case series are essential not only to increase the knowledge of the pathophysiology of this neoplasm but also to correctly evaluate the response of BCM patients to new oncological therapies.

Balloon cell melanoma: a systematic review

Balloon cell melanoma (BCM) is a rare presentation of malignant melanoma characterized by large, foamy melanocytes lacking pigmentation. This is a comprehensive review of the clinical, dermoscopic, and histological features among BCM cases reported in the literature. A systematic review of all case reports and series published since 1970 was conducted via MEDLINE, Embase, and Web of Science, using "balloon cell melanoma" and synonymous search terms. Our systematic search identified 76 cases (49% male, 51% female) of BCM in the literature. The mean age at presentation was 57.81 years. Prior skin cancer, particularly melanoma (47%), accounted for 58% of pertinent medical history. Prominent clinical exam findings included raised (46%), ulcerated (73%) lesions larger than 1 cm (68%) in the lower extremities (35%). Median Breslow thickness of primary BCM cases was 2.5 mm. Hairpin vessels (75%) and structureless architecture (75%) were predominant on dermoscopy. Notable histopathology included large (47%), vacuolated (58%) cells with foamy cytoplasm (62%) and conspicuous nucleoli (27%). Positive S-100 immunohistochemistry (73%) was most frequently employed to diagnose BCM. We observed 47% primary and 53% metastatic BCM cases. Of metastatic BCMs, balloon cells in the primary lesion were unknown in 48%, devoid in 33%, and present in 20% of cases. All metastases displayed predominant balloon cell morphology. BCM may represent an advanced phase in the progression of malignant melanoma. Improved awareness of BCM characteristics among clinicians may reduce the risk of misdiagnoses.

Balloon Cell Malignant Melanoma in a Young Female: A Case Report and Review of the Literature

Balloon cell malignant melanoma (BCMM) is a very rare malignant melanoma subtype. The clinical appearance of BCMM varies; it may be nodular, ulcerated, polypoid, papillomatous and often non-pigmented. The tumor cells histologically appear large, polygonal or round and contain abundant granular or vacuolated cytoplasm. We herein report the case of a 32-year-old female who presented with a focal eccentric pigmented mass in the left lumbar region of 15 mm in diameter that had been present for several years. She underwent tumor excision. The histopathological analysis showed epithelioid melanocytes with clear cytoplasm. An immunohistochemical analysis revealed that the cells were positive for HMB-45 and S-100 protein and negative for cytokeratin. The balloon cell component stained negative for Fontana-Masson. A month later, the patient underwent excision of the bilateral inguinal lymph nodes and metastatic BCMM was revealed. The lymph node metastases showed the complete replacement of lymph nodes by balloon cells. A diagnosis of BCMM (Breslow depth 10 mm, Clark level V) without ulcer was rendered. Staining with Ki-67 was positive in almost 44% of the balloon cells.

Balloon Cell Urethral Melanoma: Differential Diagnosis and Management

Introduction. Primary malignant melanoma of the urethra is a rare tumour (0.2% of all melanomas) that most commonly affects the meatus and distal urethra and is three times more common in women than men. Case. A 76-year-old lady presented with vaginal pain and discharge. On examination, a 4 cm mass was noted in the vagina and biopsy confirmed melanoma of a balloon type. Preoperative CT showed no distant metastases and an MRI scan of the pelvis demonstrated no associated lymphadenopathy. She underwent anterior exenterative surgery and vaginectomy also. Histology confirmed a urethral nodular malignant melanoma. Discussion. First-line treatment of melanoma is often surgical. Adjuvant treatment including chemotherapy, radiotherapy, or immunotherapy has also been reported. Even with aggressive management, malignant melanoma of the urogenital tract generally has a poor prognosis. Recurrence rates are high and the mean period between diagnosis and recurrence is 12.5 months. A 5-year survival rate of less than 20% has been reported in balloon cell melanomas along with nearly 20% developing local recurrence. Conclusion. To the best of our knowledge, this case is the first report of balloon cell melanoma arising in the urethra. The presentation and surgical management has been described and a literature review provided.

76-year-old man with a cerebellar lesion

We report a case of balloon cell melanoma metastatic to the cerebellum; the clear cell morphology prompted initial differential diagnostic considerations of metastatic renal cell carcinoma and hemangioblastoma in this site. To our knowledge this is only the second case of metastatic balloon cell melanoma to the CNS.

Carcinoid-like pattern in melanoma: report of 4 cases

Cutaneous melanoma can produce a wide variety of unusual morphological appearances, sometimes mimicking other tumors. We report on 4 cases of melanoma with carcinoid-like features, namely, arrangement of neoplastic cells in trabecules, ribbons, pseudorosettes, rosettes, and/or small round islands. A total of 10 biopsies from 4 patients were available for a histopathological study comprising congenital nevus, a nodule that had developed in this nevus and its persistence/recurrence, 3 primary cutaneous lesions, 3 metastases, and a recurrent/persistent lesion. In 7 of these 10 lesions, the most characteristic finding was a distinctive arrangement of the neoplastic cells as trabecules, ribbons, pseudorosettes, rosettes, or small round insular islands, thus closely resembling cell arrangement in carcinoids of various organs. All these tumors were positive for melanocytic markers. No neuroendocrine differentiation was demonstrated immunohistochemically. We conclude that the carcinoid-like pattern in melanoma, namely, the pattern in which neoplastic cells are arranged in trabecules, ribbons, cords, rosettes, pseudorosettes, and small round insular nests resembling those in carcinoids, is a distinctive pattern, which may rarely occur in primary cutaneous melanoma, its recurrence or metastasis, or in a melanoma associated with a large congenital nevus. This morphological type of melanoma may produce a serious diagnostic pitfall, but despite a confusing microscopic appearance, these tumors seem to demonstrate a conventional immunohistochemical profile.

Follicular stem cell carcinoma: histologic, immunohistochemical, ultrastructural, and clinical characterization in 30 dogs

Diagnostic records of 30 primary and one metastatic follicular stem cell carcinomas in 30 dogs were reviewed. Neoplastic cells had a clear cytoplasm and formed lobules and nests surrounded by a basement membrane. Trichoepitheliomatous and apocrine differentiations were noted in 22 of 30 (73%) and 21 of 30 (70%) primary tumors, respectively. Glycogen was present in 20 of 20 (100%) tumors tested, suggesting tricholemmal differentiation. Antibodies against AE1/AE3 cytokeratin, vimentin, and melanA/MART1 stained 29 of 30 (97%), 29 of 30 (97%), and 12 of 27 (44%) primary tumors, respectively. Small amounts of melanin were identified in 14 primary tumors, either on the hematoxylin and eosin-stained section (n = 6), or on the Fontana-stained section (n = 8 of 14). Ultrastructural features of neoplastic cells included cell junction complexes, swollen mitochondria, neuroendocrine-like granules, and intracytoplasmic non-membrane-bound accumulation of proteinaceous material. Features of this neoplasm are consistent with a follicular stem cell origin. Follow-up information was available for eight dogs. Metastases developed in the draining lymph node at the time of excision of the primary tumor (n = 1) or subsequently (n = 3).

Balloon cell melanoma in three dogs: a histopathological, immunohistochemical and ultrastructural study

Balloon cell melanoma, a variant of malignant melanoma, has been reported on rare occasions in animals and is uncommon in man. Such tumours have variable numbers of large, round to polygonal cells with abundant, clear, often vacuolated cytoplasm containing fine melanin granules and variable amounts of lipid. This report describes balloon cell melanomas in three dogs. Immunohistochemically, these tumours showed reactions similar to those of human melanomas when tested with antibodies against S-100 protein, neuron-specific enolase (NSE) and vimentin. Electron microscopically, numerous heterogeneous melanosomes were demonstrated in the balloon cell cytoplasm of one tumour. Although balloon cell melanoma apparently occurs infrequently in dogs, it should always be considered in the differential diagnosis of neoplasms containing clear cells.

Morphological and immunophenotypic variations in malignant melanoma

A variety of cytomorphological features, architectural patterns and stromal changes may be observed in malignant melanomas. Hence, melanomas may mimic carcinomas, sarcomas, benign stromal tumours, lymphomas, plasmacytomas and germ cell tumours. Melanomas may be composed of large pleomorphic cells, small cells, spindle cells and may contain clear, signet-ring, pseudolipoblastic, rhabdoid, plasmacytoid or balloon cells. Various inclusions and phagocytosed material may be present in their cytoplasm. Nuclei may show bi- or multi-nucleation, lobation, inclusions, grooving and angulation. Architectural variations include fasciculation, whorling, nesting, trabeculation, pseudoglandular/pseudopapillary/pseudofollicular, pseudorosetting and angiocentric patterns. Myxoid or desmoplastic changes and very rarely pseudoangiosarcomatous change, granulomatous inflammation or osteoclastic giant cell response may be seen in the stroma. The stromal blood vessels may exhibit a haemangiopericytomatous pattern, proliferation of glomeruloid blood vessels and perivascular hyalinization. Occasionally, differentiation to nonmelanocytic structures (Schwannian, fibro-/myofibroblastic, osteocartilaginous, smooth muscle, rhabdomyoblastic, ganglionic and ganglioneuroblastic) may be observed. Typically melanomas are S100 protein, NKIC3, HMB-45, Melan-A and tyrosinase positive but some melanomas may exhibit an aberrant immunophenotype and may express cytokeratins, desmin, smooth muscle actin, KP1 (CD68), CEA, EMA and VS38. Very rarely, neurofilament protein and GFAP positivity may be seen.

Epidermotropic xanthoma mimicking balloon cell melanoma

Xanthomas of the skin may mimic balloon cell melanoma because 1) both lesions may exhibit a diffuse dermal proliferation of cytologically similar large vacuolated or clear cells with distinct cytoplasmic membranes, 2) dermal maturation (smaller deep dermal nuclei) is absent in both lesions, 3) melanin pigment is usually absent in balloon cell melanoma, 4) cellular atypia may be minimal in balloon cell melanoma, and 5) mitoses may be absent or rare in balloon cell melanoma. We report a unique xanthoma, which further simulated melanoma by exhibiting epidermotropism and a pseudonesting pattern at the dermal-epidermal junction. The correct diagnosis was made with an immunohistochemical panel revealing tumor cell positivity for CD68 and negativity for S-100 protein and MART-1. Immunohistochemical studies may be required in the critical differential diagnosis of epidermotropic xanthoma and amelanotic balloon cell melanoma.

Malignant melanoma masquerading as malignant fibrous histiocytoma

Numerous cytological variants of malignant melanoma (MM) exist. We report two cases of MM resembling malignant fibrous histiocytoma (MFH). Pathologists should be aware of this variant. Possible pitfalls that could lead to an incorrect diagnosis are discussed.

Dermatopathologic variants of malignant melanoma

An appropriate biopsy is the pivotal procedure that facilitates accurate histopathologic diagnosis of a pigmented skin lesion. Excisional skin biopsy is the method of choice for removing a suspected malignant melanoma. More than 95% of malignant melanomas that involve the skin belong to one of the four most common clinicopathologic categories: superficial spreading, nodular, lentigo maligna, and acral lentiginous melanoma. A small but important group of cutaneous melanomas can be classified as unusual variants. Many of these unusual variants have a distinct histopathologic appearance; they include desmoplastic melanoma, neurotropic melanoma, pedunculated melanoma, metastatic melanoma, amelanotic melanoma, melanoma arising within a benign nevus, regressing ("invisible") melanoma, and balloon cell melanoma. Other lesions may simulate malignant melanoma histopathologically. Immunohistochemical stains, such as S-100 protein, vimentin, keratin, and HMB-45, are useful for distinguishing these lesions from true melanoma.

Balloon cell metastatic melanoma: an important differential in the diagnosis of clear cell tumours

Two cases of metastatic balloon cell melanoma are reported. Each tumour was composed of large clear cells which did not contain melanin, glycogen or fat, but showed positive staining for S-100 protein, NK/1-C3 and HMB-45. In each case the primary lesion was a cutaneous melanoma of typical morphology. It is essential to consider balloon cell melanoma in the differential diagnosis of clear cell tumours. These cases emphasize the need for an accurate clinical history.

Balloon cell malignant melanoma of the skin. A clinicopathologic study of 34 cases with histochemical, immunohistochemical, and ultrastructural observations

Balloon cell malignant melanoma (BCMM) is a rare histologic variant of malignant melanoma (MM). Thirty-four patients with BCMM from the files of the Armed Forces Institute of Pathology (AFIP) were studied by means of clinicopathologic correlation and histochemical, immunohistochemical, and ultrastructural methods to better define this entity. The cytoplasmic features of the balloon cells observed in BCMM resemble those noticed in balloon cell nevus (BCN), but the presence of nuclear pleomorphism, atypia, and mitoses and the absence of intervening stroma help distinguish BCMM. The cells also show many histochemical, immunochemical, and ultrastructural features of conventional melanoma cells. Although it is generally believed that balloon melanoma cells represent a degenerative change, the immunohistochemical and electron microscopic findings suggest that the balloon tumor cells are most likely metabolically active melanocytic cells. Microscopically, BCMM also must be differentiated from other clear cell tumors such as clear cell sarcoma (MM of soft parts), hibernoma, xanthoma, sebaceous neoplasms, metastatic renal cell carcinoma, (malignant) clear cell acrospiroma, (malignant) granular cell tumor, granular (clear) cell basal cell carcinoma, clear cell syringoma, and atypical fibroxanthoma. The prognosis of BCMM usually correlates with the tumor thickness similar to that in other histologic types of cutaneous MM. Nineteen (57.5%) of 33 patients with adequate follow-up information died of disseminated tumors from 2 months to 12 years after the initial treatment. Six (18.2%) patients developed local recurrences: four of these patients died of metastasis and two were alive with metastatic tumor at last contact. Five (15.2%) patients were alive with metastatic tumors, and seven (21.2%) were alive without evidence of disease at last contact. Recognition of BCMM is important because of its malignant biologic behavior.

Histopathologic diagnosis of pigmented lesions of the skin

The present review deals with the histopathologic diagnosis of the commonest pigmented lesions of the skin with emphasis on melanocytic tumors. The discussed entities are systematized in pigmented lesions with and without an increase in the number of melanocytes, i.e. melanocytic hyperplasia, and in those that actually are melanocytic neoplasias. Histopathological, ultrastructural, and immunohistochemical features of relevance for the differential diagnosis are discussed in depth. One section is dedicated to the immunohistochemical markers of melanocytic lesions, the other one to the electron microscopy of malignant melanoma. Neoplasms simulating malignant melanoma and the less frequent variants of this tumor are also discussed. The diagnosis of pigmented lesions of the skin represents one of the most frequent and difficult challenges in dermatopathology, and useful clues for the differential diagnosis, especially of melanocytic dysplasias and neoplasias, are presented in the present article.

Balloon cell melanoma mimicking clear cell carcinoma

Balloon cells may occur in both benign nevi and malignant melanomas. Sometimes they dominate the histological appearance and cause difficulties in biopsy interpretation. There are no specific clinical characteristics. We report a metastatic balloon cell melanoma where the primary tumour was not identified and the histological appearance mimicked that of a clear cell renal carcinoma.

Balloon cell melanoma: a report of two cases

Two cases of balloon cell malignant melanoma of the skin are reported. The first lesion was pigmented, the second was amelanotic. Histologically, the tumor mass was dermal and intraepidermal and almost exclusively composed of balloon cells. Many of the clear cells demonstrated postivity with the S-100 protein immunostaining. The problems of clear-cell tumor differential diagnosis are discussed.