CUTANEOUS MYXOID CYST. A CLINICOPATHOLOGICAL AND HISTOCHEMICAL STUDY

Republication of "Mucous Cyst at the Interphalangeal Joint of the First Toe Caused by Contact Pressure With the Second Toe due to Hallux Valgus: A Case Report"

A 77-year-old woman presented with a mucous cyst on the lateral aspect of the interphalangeal joint of the first toe caused by contact pressure with the second toe from hallux valgus. She complained of discomfort and discharge from the left first toe for approximately 4 months. Physical examination showed the second toe pressing strongly against the first toe due to hallux valgus and discharge from the skin on the lateral aspect of the interphalangeal joint of the first toe. Magnetic resonance imaging showed a cystic lesion at the same level. The patient underwent a modified scarf osteotomy of the first metatarsal for hallux valgus to resolve the contact pressure between the toes-considered the cause of the mucous cyst-and resection of mucous cyst. Forefoot weight bearing was allowed 6 weeks after surgery. As of 1 year after surgery, she has had no recurrence of the cyst. The score on the Japanese Society for Surgery of the Foot hallux metatarsophalangeal-interphalangeal scale improved from 59/100 points to 92/100. This outcome suggests that hallux valgus correction should be considered when a mucous cyst is associated with contact pressure due to a hallux valgus deformity. To the best of our knowledge, there are no previous reports of a mucous cyst caused by contact pressure between the first toe and second toe due to hallux valgus.

Cd34+ Stromal Cells/Telocytes in Normal and Pathological Skin

We studied CD34+ stromal cells/telocytes (CD34+SCs/TCs) in pathologic skin, after briefly examining them in normal conditions. We confirm previous studies by other authors in the normal dermis regarding CD34+SC/TC characteristics and distribution around vessels, nerves and cutaneous annexes, highlighting their practical absence in the papillary dermis and presence in the bulge region of perifollicular groups of very small CD34+ stromal cells. In non-tumoral skin pathology, we studied examples of the principal histologic patterns in which CD34+SCs/TCs have (1) a fundamental pathophysiological role, including (a) fibrosing/sclerosing diseases, such as systemic sclerosis, with loss of CD34+SCs/TCs and presence of stromal cells co-expressing CD34 and αSMA, and (b) metabolic degenerative processes, including basophilic degeneration of collagen, with stromal cells/telocytes in close association with degenerative fibrils, and cutaneous myxoid cysts with spindle-shaped, stellate and bulky vacuolated CD34+ stromal cells, and (2) a secondary reactive role, encompassing dermatitis—e.g., interface (erythema multiforme), acantholytic (pemphigus, Hailey–Hailey disease), lichenoid (lichen planus), subepidermal vesicular (bullous pemphigoid), psoriasiform (psoriasis), granulomatous (granuloma annulare)—vasculitis (leukocytoclastic and lymphocytic vasculitis), folliculitis, perifolliculitis and inflammation of the sweat and sebaceous glands (perifolliculitis and rosacea) and infectious dermatitis (verruca vulgaris). In skin tumor and tumor-like conditions, we studied examples of those in which CD34+ stromal cells are (1) the neoplastic component (dermatofibrosarcoma protuberans, sclerotic fibroma and solitary fibrous tumor), (2) a neoplastic component with varying presentation (fibroepithelial polyp and superficial myxofibrosarcoma) and (3) a reactive component in other tumor/tumor-like cell lines, such as those deriving from vessel periendothelial cells (myopericytoma), epithelial cells (trichoepithelioma, nevus sebaceous of Jadassohn and seborrheic keratosis), Merkel cells (Merkel cell carcinoma), melanocytes (dermal melanocytic nevi) and Schwann cells (neurofibroma and granular cell tumor).

Digital mucous cyst: Altered epidermal mucin as a clue to diagnosis

BACKGROUND

Digital mucous cyst (DMC) is histopathologically characterized by accumulation of mucin in the dermis. Some cases of DMC also show epidermal mucin, the histopathologic appearance and staining properties of which have not been described in detail.

METHODS

A total of 24 cases of DMC were investigated by routine hematoxylin-eosin (H&E) and Alcian blue stains in addition to AE1/AE3 immunohistochemistry.

RESULTS

Nine out of the 24 cases of DMC showed epidermal mucin. As the epidermal mucin migrates upward within the epidermis, it transforms from a flocculent granular substance into one or several solid horizontal plugs with a more homogeneous appearance and incorporates cytoplasmic fragments of keratinocytes/corneocytes. The homogeneous mucin plugs stain eosinophilic or amphophilic with an H&E formulation using hematoxylin 7212 and basophilic with Gill 3 or Harris's hematoxylin. The eosinophilic staining is enhanced when the eosin solution contains phloxine.

CONCLUSIONS

The variably eosinophilic, amphophilic, or basophilic staining of epidermal mucin can be explained by its composition of basophilic mucin and eosinophilic debris from cytoplasmic fragments. The eosinophilic staining of mucin has not been reported before and can be diagnostically important because it may be mistaken for serum exudate.

Mucous Cyst at the Interphalangeal Joint of the First Toe Caused by Contact Pressure With the Second Toe due to Hallux Valgus

A 77-year-old woman presented with a mucous cyst on the lateral aspect of the interphalangeal joint of the first toe caused by contact pressure with the second toe from hallux valgus. She complained of discomfort and discharge from the left first toe for approximately 4 months. Physical examination showed the second toe pressing strongly against the first toe due to hallux valgus and discharge from the skin on the lateral aspect of the interphalangeal joint of the first toe. Magnetic resonance imaging showed a cystic lesion at the same level. The patient underwent a modified scarf osteotomy of the first metatarsal for hallux valgus to resolve the contact pressure between the toes— considered the cause of the mucous cyst—and resection of mucous cyst. Forefoot weight bearing was allowed 6 weeks after surgery. As of 1 year after surgery, she has had no recurrence of the cyst. The score on the Japanese Society for Surgery of the Foot hallux metatarsophalangeal-interphalangeal scale improved from 59/100 points to 92/100. This outcome suggests that hallux valgus correction should be considered when a mucous cyst is associated with contact pressure due to a hallux valgus deformity. To the best of our knowledge, there are no previous reports of a mucous cyst caused by contact pressure between the first toe and second toe due to hallux valgus.

Surgical treatment of mucous cysts by subcutaneous excision and osteophyte resection: Results in 68 cases at a mean 6.63 years' follow-up

The goal of this study was to assess the results of treatment of mucous cysts by subcutaneous excision and osteophyte resection without an associated skin procedure. From 1993 to 2013, 81 mucous cysts were operated on. In 27 cases, a nail deformity was present. Obvious osteoarthritis was present in 84% of cases. Among them, 67 patients (68 cysts) were subsequently assessed through a phone questionnaire after a mean follow-up of 6.6 years. Patients who reported a recurrence or suspected one were reassessed in consultation. Among the 68 evaluated cases, two developed an infection and one had delayed skin healing; these complications occurred on cysts with a previous fistula. In one case (1.5%), a recurrence was observed four months after excision of a subungual cyst. All nail deformities had resolved; 53 patients felt no discomfort and 65 were very satisfied or satisfied with the procedure and would undergo surgery again. The recurrence rate of 1.5% is consistent with that of other studies where the same procedure was used, without cutaneous grafting, ranging from 0 to 2%. This result is better than in studies where a graft or a flap was performed without systematic joint debridement. Our procedure is sufficient to effectively treat mucous cysts with less morbidity. Complications are rare and occur only in cysts associated with a fistula, justifying their early surgical treatment.

Solitary superficial acral angiomyxoma: an infrequently reported soft tissue tumor

Superficial angiomyxomas (SA) are clinically variable, infrequent, benign skin lesions. They are usually located on the trunk, but can also appear on the lower limbs, head, and neck. The present case, hence, is unusual, because the lesion developed on the toe. They are diagnosed histologically, and are characterized by being poorly delimited tumors with the presence of interstitial myxoid material and scanty cellularity. We discuss the clinical and histological features of digital SA as well as a brief outline of other myxoid lesions.

Two cases of myxoma of the external auditory canal

Myxomas were found in the outer ear canal of a 66-year-old female and a 51-year-old male. Both tumors were soft and sessile and located at the antero-superior part of the external auditory canal near the eardrum. Profuse, clear mucus was seen when the tumor ruptured or was incised. Histology showed spindle-shaped and stellate cells in myxoid extracellular matrix. CT images revealed a small bone defect adjacent to the tumor in the meatal bone. This bony defect was confirmed during surgery. The bony defects seen in both cases may have something to do with the genesis of the tumor. We found only 5 sporadic cases, including ours, reported in the English literature. As myxoma of the outer ear canal is also reported in 18 patients as a symptom of Carney's complex, we must check for accompanying symptoms of the complex such as spotty skin pigmentation, endocrine tumors, or schwannoma. Total removal of the tumor is necessary to prevent recurrence.

Oral Focal Mucinosis of the Tongue: A Rare Clinical Case

Oral focal mucinosis (OFM) is a rare mucosal lesion of unknown etiopathogenesis. It is considered the oral counterpart of cutaneous focal mucinosis. From the anatomo-pathological point of view it is characterised by a focal degeneration of myxoid type of connective tissue. A literature survey revealed 50 reports of OFM cases worldwide. Here, we present an even more rare case with tongue involvement. Particular emphasis is placed on diagnostic-differential aspects of this kind of lesion, both from the clinical and the histopathological point of view, in respect to other manifestations of tongue mucosa.

Digital Mucous Cysts

Background:

Digital mucous cyst (DMC) is a common benign condition, but consensus has not been reached regarding its pathogenesis and treatment.

Objective:

This review provides a concise overview of DMCs.

Methods:

The review presents the literature pertaining to the etiology, pathogenesis, classification, clinical features, epidemiology, differential diagnoses, diagnosis, and management of DMCs.

Results:

DMCs have a predilection for middle-aged patients, a good prognosis, and a high recurrence rate. DMCs may occur in one of three locations on the distal digit. They arise owing to a metaplastic or degenerative process. Preexisting osteoarthritis is common and may be an etiologic factor in patients with DMCs. A number of conservative and surgical treatments are available depending on the structures and locations involved.

Conclusion:

Studies with greater sample size and longer follow-up would enrich current knowledge of the benefits, recurrences, and complications for each treatment modality.

Running GAGs: myxoid matrix in tumor pathology revisited: what's in it for the pathologist?

Ever since Virchow introduced the entity myxoma, abundant myxoid extracellular matrix (ECM) has been recognized in various reactive and neoplastic lesions. Nowadays, the term "myxoid" is commonly used in daily pathological practice. But what do today's pathologists mean by it, and what does the myxoid ECM tell the pathologist? What is known about the exact composition and function of the myxoid ECM 150 years after Virchow? Here, we give an overview of the composition and constituents of the myxoid ECM as known so far and demonstrate the heterogeneity of the myxoid ECM among different tumors. We discuss the possible role of the predominant constituents of the myxoid ECM and attempt to relate them to differences in clinical behavior. Finally, we will speculate on the potential relevance of this knowledge in daily pathological practice.

Digital superficial angiomyxoma

Superficial angiomyxoma is a rare, distinctive cutaneous soft-tissue neoplasm, which shows a prominent myxoid matrix with numerous blood vessels. This condition usually presents with a nodular lesion on the trunk, head and neck, or the genital region. We describe a case of superficial angiomyxoma, which presented at an unusual digital location while also demonstrating the features of transepidermal elimination, and which mimicked a digital myxoid cyst.

Multiple myxoid cysts secondary to occupation

We report the case of a 50-year-old woman who presented with eight digital myxoid cysts (DMCs) involving the fingers of both hands. They developed within 12 months of the patient starting a job that involved pushing a garment into an embroidery mould, thus exerting a downward force on the fingertips. The pressure exerted from this force could have potentially damaged the joint synovial capsule, leading to rupture and loss of synovial gel, thus inducing myxoid cysts. This case suggests that DMCs may be related to occupation, and to our knowledge, this is only the second reported case of occupationally induced DMCs.

Myxoid tumours of soft tissue

Myxoid tumours of soft tissue encompass a heterogeneous group of lesions characterized by a marked abundance of extracellular mucoid (myxoid) matrix. This group of tumours demonstrate significant variability in their biological behaviour thus including tumours which are entirely harmless, tumours with a tendency to recur locally but not metastasize, and malignant tumours. There appears to be a considerable degree of overlap clinically and morphologically between the various tumour types in this group, generating potential diagnostic problems for the clinician and pathologist alike. While diligent microscopy remains the basis of diagnostic pathology, the continuous developments and refinements within the fields of immunohistochemistry and molecular cytogenetics are providing substantial new information, allowing the development of new diagnostic criteria and hence facilitating an accurate diagnosis. It is the aim of this short review to highlight the most prevalent soft tissue tumours with predominantly myxoid morphology, to describe the features by which the majority of these myxoid lesions may be identified, and to discuss the differential diagnosis where appropriate.

Superficial angiomyxoma: clinicopathologic analysis of a series of distinctive but poorly recognized cutaneous tumors with tendency for recurrence

Despite being first described in 1988, superficial angiomyxoma is still a poorly recognized cutaneous tumor. Although its histologic features are distinctive, its existence seems not to be widely accepted. We analyzed the clinicopathologic and immunohistochemical features in a series of 39 cases. Twenty-five patients were males; age range was birth to 82 years (median, 45.5 years). Most cases presented as cutaneous papules, nodules, or polypoid lesions. Seventeen tumors arose on the trunk, 14 on the head and neck, and seven on the lower limbs. All cases were treated by local excision, and eight recurred locally. In four of the latter cases, there were two recurrences. Histologically, the lesions were dermal with variable involvement of the subcutis. Tumors were poorly circumscribed, but a focal lobular outline was always identified. Distinctive histologic features included extensive myxoid stroma, numerous small blood vessels, varying cellularity, acellular mucin pools, stellate or bipolar fibroblastic cells, muciphages, a sparse, mixed inflammatory cell infiltrate with notable neutrophils, and occasional plumper cells with eosinophilic cytoplasm. Cytologic atypia was mild at most, and mitotic figures were rare. In approximately 20% of cases, the primary lesion or its recurrence contained epithelial structures, including epidermoid cysts, thin strands of squamous epithelium, and small buds of basaloid cells. Immunohistochemically, tumor cells were negative for S-100 protein, smooth muscle actin, and pan-keratin. We support the concept of superficial angiomyxoma as a distinctive clinicopathologic entity that should be included in the differential diagnosis of other myxoid cutaneous tumors, including dermal nerve sheath myxoma, trichodiscoma and trichofolliculoma, and low-grade myxofibrosarcoma.

Intraosseous ganglion cysts of the ankle: a report of three cases with long-term follow-up

Three cases of intraosseous ganglion cysts of the ankle are presented with an average follow-up of 68 months (range, 48-78 months). Review of the literature revealed 251 cases of intraosseous ganglion cysts, with 75 located in the ankle and a recurrence rate of 6.1%. In the three cases presented, a satisfactory long-term result was obtained with bone graft and curettage in two cases and currettage alone in one case. No recurrences or complications occurred.

Myxoid dermatofibroma

AIMS

This report presents seven cases of a rare variant of dermatofibroma, characterized by marked mucinous stromal changes.

METHODS AND RESULTS

In this retrospective clinicopathological study, lesions preferentially occurred on the lower extremities of young to middle-aged females. Clinical (differential) diagnoses included: dermatofibroma (two cases), cyst, tophus, ganglion and neurofibroma. Histology revealed well circumscribed, faintly stained dermal to subcutaneous lesions which contained abundant stromal mucin. A variable amount of spindle-shaped cells, occasional lymphocytes and fine collagen fibres were also seen. Epidermal hyperplasia above as well as storiform arrangement of spindle cells and some sclerotic collagen at the periphery of the lesion indicated the fibrohistiocytic origin. Individual histopathological features included: bizarre giant cells, perifollicular arrangement and seas of mucin with pseudovascular clefts in one case each. Immunohistochemically, all lesions were positive for KiM1p (> 50% of the cells). Moreover, two lesions showed moderate reactivity for factor XIIIa (10-25%), one each with NK1C3 (> 90%) and smooth muscle actin (50%), but were otherwise negative with a broad panel of markers. Electron microscopy in one case revealed large pools of mucin interspersed by a moderate number of fibrocytes with fine fibrillary collagen.

CONCLUSION

This series confirms myxoid dermatofibroma as a rare variant of fibrohistiocytic tissue response; our series also indicates that many of these lesions might be misinterpreted as cutaneous myxoma.

Myxoid malignant fibrous histiocytoma mimicking papular mucinosis

Malignant fibrous histiocytoma is the most common type of soft tissue sarcoma in late adulthood. The myxoid variant of malignant fibrous histiocytoma, also known as myxofibrosarcoma, can develop in subcutaneous rather than deep soft tissue, and the true extent of these superficial tumors is often underestimated. Patients with these low-grade myxoid malignant fibrous histiocytomas have an excellent 5-year survival rate, and it is therefore important to recognize them. We present a case with a superficial cutaneous accumulation of mucin that was diagnosed clinically and histologically as papular mucinosis. In retrospect, a subcutaneous presentation of myxofibrosarcoma should have been considered.

Oral focal mucinosis of the tongue

Oral focal mucinosis (OFM) is an uncommon clinicopathological entity which is considered to be the oral counterpart of cutaneous focal mucinosis and cutaneous myxoid cyst. It is comprised of a clinically elevated mass with a histological feature of localised areas of myxomatous connective tissue. The present study adds a rare case of OFM of the tongue to the literature, and we present a review of the most characteristic oral myxomatous lesions.

Synovial cysts: clinical and neuroradiological aspects

Lumbar and intraneural synovial cysts are uncommon lesions, although their incidence has increased since the introduction of MRI. The authors describe the results of a study comprising 23 patients with synovial cyst (5 lumbar, 19 intraneural). Neuroradiological investigations included CT scan and MRI; however, it was not always possible to diagnose the nature of the lesion. In 18 cases the lesion was removed totally including its capsule; in the other 5 cases it was removed subtotally. Seven of the 23 patients presented a total remission of symptoms/signs, 11 improved and 5 remained unchanged. The importance of treating synovial cysts as radically as possible is discussed together with their most significant clinical and neuroradiological aspects.

[Mucoid cysts of the distal interphalangeal joints of the fingers. Apropos of a prospective series (100 cases)]

100 mucous cysts of distal interphalangeal joint were treated by a radical excision that involved skin, cyst and dorsal capsular structures. The follow up was 2 years minimum, only two recurrence were noted, with other procedure the tate of recurrence is higher (10 to 20%). The proposed procedure is based on two hypothegenesis: skin localisation of mucous jelly, and degeneration of dorsal capsular structure of an arthritic joint.

Intraosseous ganglion cyst of the lunate: diagnosis and management

Intraosseous ganglion cyst of the lunate is an uncommon lesion and cause of wrist pain. Histopathologically it is identical to the common dorsal wrist ganglion and treatment by arthrotomy, curettage of the ganglion and bone graft resulted in clinical improvement in nine patients, six of whom became symptom-free.

Focal mucinosis (myxoid cyst). Surgical therapy

Myxoid cysts typically arise in association with distal interphalangeal joint arthritis. When myxoid cysts become problematic, surgical excision is a standard treatment with a high cure rate and few complications. The origin, anatomy, and alternative medical and surgical treatment options are discussed.

Preoperative diagnosis of an extradural cyst arising from a spinal facet joint: case report

A case of a lumbar spinal extradural cyst is reported. An accurate preoperative diagnosis was made using magnetic resonance imaging. Characteristic findings on magnetic resonance imaging obviate the need for any additional radiological studies. The clinical features, radiological findings, and pathogenesis of these lesions are discussed.

Oral focal mucinosis

Oral focal mucinosis (OFM) is an uncommon clinicopathological entity which is considered to be the oral counterpart of cutaneous focal mucinosis and/or cutaneous myxoid cyst. It is comprised of a clinically elevated mass with a histological picture of localized areas of myxomatous connective tissue. The present study adds 15 new cases of OFM to the literature and analyzes their clinical, histological and histochemical features. Most of the lesions were located in the gingiva and alveolar mucosa. The nature of the lesion is unclear and it is suggested that the mucinous accumulation is the result of fibroblastic overproduction of hyaluronic acid.

Myxoma of the skin of a finger

A case of a true myxoma of the fingertip is presented. The lesion was removed by simple shave excision. Reports of myxoma of the skin are reviewed, and the differential diagnosis of this rare tumor is discussed.

Dermal nerve sheath myxoma: a study of three cases

Three cases of dermal nerve sheath myxoma have been studied by light microscopy, histochemistry and immunohistochemistry. The pertinent literature has been reviewed. This lesion, which is a rare benign tumour of probable nerve sheath origin, arises most often in young adults and shows a predeliction for females. Histologically it has a characteristic appearance. Histochemically, the heteroglycan content of the mucoid matrix is more in keeping with a cartilaginous lesion. The histogenesis and differential diagnosis are discussed.

The cutaneous mucinoses

The cutaneous mucinoses are a group of connective tissue disorders characterized by the deposition of mucin, either focally or diffusely, in the interstices of the dermis. The diseases may be a primary (metabolic) or secondary (catabolic) process. Systemic abnormalities are seen with most of these disorders. This review discusses the primary mucinoses in which the predominant dermal mucin is hyaluronic acid. Current therapy and proposed mechanisms for the mucinoses are considered.

The treatment of mucous cysts: long-term follow-up in sixty-two cases

To determine the course of the so-called mucous cyst both after various modalities of treatment and without treatment, 56 patients with 62 cysts were contacted to participate in a study with an average follow-up of 6.2 years after initial evaluation. The mucous cysts primarily occurred in elderly women and were most prevalent in the index and long fingers. Longitudinal grooving of the nail was not uncommon and may hve preceded the appearance of the cyst. Degeneration of the distal interphalangeal joint was frequently found. The long-term results after treatment with simple aspiration or decapping, or by excision with skin grafts and flaps as needed or with observation only were similar. However, surgical excision or aspiration may eliminate earlier the cosmetic disfigurement and occasional discomfort that are associated with this lesion.

Self-healing juvenile cutaneous mucinosis

A case of self-healing juvenile cutaneous mucinosis is presented. It demonstrates typical features of the disease: early age of onset, infiltrated plaque lesions of the head and torso, nodules of the face and periarticular regions, rapid onset accompanied by inflammatory phenomena, and spontaneous resolution over a few months. Skin biopsy showed the deposition of the mucin, hyaluronic acid, mainly in the upper reticular dermis, and a mild increase in fibroblasts and mast cells. Results of studies of B and T lymphocytes were normal. Although three cases have been reported in Europe, to our knowledge this is the first reported case in the English-language literature.

A Ganglion Arising over the Acromioclavicular Joint: A Case Report

Ganglion cysts are a common entity arising around joints and tendon sheaths. We present a previously unreported location for a ganglion and review the various theories on etiology, pathogenesis, and treatment. With yet another unusual location for ganglia, over the acromioclavicular joint, we propose ganglia should be considered in the differential diagnosis of masses arising near any synovial joint or tendon sheath.