Folliculotropic mycosis fungoides associated with follicular mucinosis: A case report and mini review

Key Clinical Message

F-MF is a rare non-classic variant of MF. In the case of hair loss, this should be a diagnostic consideration. The essence of the diagnosis of F-MF is a careful medical history, physical examination, and a combination of immunohistological and molecular analyses (Cureus. 2022; 14:e21231, Ann Saudi Med. 2012; 32:283, Oman Med J. 2012; 27:134, Int J Dermatol. 2016; 55:1396, Saudi Med J. 2018; 39:994 and Case Rep Oncol. 2018; 11:436).

Abstract

Mycosis fungoides (MF) is a primary cutaneous T-cell lymphoma with multiple subtypes. Follicular MF (F-MF) is a non-classic variant of MF. Histological features entail folliculotropism and damage of the epithelium lining of the hair follicles with or without mucin deposition. A 52-year-old male patient complained of recurrent skin lesions on the scalp over 8 months. The lesions appeared suddenly, enlarged over time, and became itchy. A skin punch biopsy was performed. Histological features included mucin deposits in the epithelium of the hair follicles and dense, predominantly perifollicular atypical lymphocytes infiltrating the follicular epithelium. The lymphoid cells were composed of CD3-positive T cells (CD4/CD8-positive T cells) with a shift in favor of the former. The case was diagnosed as F-MF on an immunohistological basis. The diagnosis of F-MF is often difficult for dermatologists and dermatopathologists alike. Not only clinicopathological correlations but also immunohistochemical and molecular analysis are required.

An update on long-term outcomes of pediatric follicular mucinosis over a 20-year period: a retrospective cohort study

BACKGROUND

Follicular mucinosis (FM) is a rare disease characterized by mucin accumulation in the follicular unit. FM's etiology is still widely debated since its first description in 1957. Follicular mucinosis is usually reported to be benign in children, although reports of malignant transformation, most commonly mycosis fungoides, exist. The present project aims to demonstrate that children with a diagnosis of follicular mucinosis have positive long-term outcomes and do not develop mycosis fungoides.

MATERIALS AND METHODS

This is a retrospective cohort study where patients with a diagnosis of follicular mucinosis ages 22 years and below were identified. Data surrounding the patient's diagnosis of FM, differential diagnosis, treatments, and long-term outcomes were collected. Patients who were lost to follow-up were contacted by phone for an update on the status of their skin and overall health.

RESULTS

Out of 14 patients with follow-up information, none developed subsequent mycosis fungoides or other hematologic malignancies.

CONCLUSION

Pediatric patients with follicular mucinosis will likely present with limited disease and not experience malignant transformation.

Primary cutaneous T-cell lymphomas in childhood and adolescence

Primary cutaneous lymphomas are extranodal non-Hodgkin lymphomas of T- or B- cell origin, that predominantly affect older patients but have been reported in all age groups and as early as in the first years of life. Diagnosis of cutaneous lymphomas is challenging and requires high clinical suspicion and close collaboration between dermatologists, pediatric oncologists and pathologists. Skin involvement of non-Hodgkin lymphomas in children or adolescents can either be primary cutaneous or secondary due to an underlying nodal lymphoma. The most common primary cutaneous lymphomas encountered in children are of T-cell origin, with mycosis fungoides being the most prevalent cutaneous T-cell lymphoma, followed by CD30⁺ lymphoproliferative disorders. While cutaneous lymphomas share clinicopathologic characteristics between juvenile and adult forms, there are important differences in terms of clinical presentation, diagnosis and treatment. The hypopigmented variant of mycosis fungoides seems to be overrepresented in the pediatric age group. Prognosis and treatment of mycosis fungoides are stage dependent. The majority of children present with early-stage disease and respond well to topical corticosteroids and phototherapy.

Primär kutane T‐Zell‐Lymphome im Kindes‐ und Jugendalter

Primär kutane Lymphome sind extranodale T- oder B-Zell-Non-Hodgkin-Lymphome, die vorwiegend ältere Patienten betreffen, aber in allen Altersgruppen einschließlich der ersten Lebensjahre auftreten können. Die Diagnose kutaner Lymphome ist eine Herausforderung und erfordert einen hohen klinischen Verdacht sowie enge Zusammenarbeit zwischen Dermatologen, pädiatrischen Onkologen und Pathologen. Generell müssen primär kutane Lymphome von sekundär kutanen Lymphomen, welche meist von nodalen oder extranodalen Lymphomen ausgehen, unterschieden werden. Die häufigsten primär kutanen Lymphome im Kindesalter sind T-Zell Lymphome, wobei Mycosis fungoides das häufigste kutane T-Zell-Lymphom darstellt, gefolgt von CD30+ lymphoproliferativen Erkrankungen. Während klinisch-pathologische Merkmale kutaner Lymphome bei Jugendlichen und Erwachsenen ähnlich sind, gibt es wichtige Unterschiede bezüglich klinischer Präsentation, Diagnose und Behandlung. Die hypopigmentierte Variante der Mycosis fungoides scheint in der pädiatrischen Altersgruppe überrepräsentiert zu sein. Prognose und Behandlung der Mycosis fungoides sind stadienabhängig. Die Mehrheit der Kinder weist ein frühes Krankheitsstadium auf und spricht gut auf topische Kortikosteroide und Phototherapie an.

Follicular mucinosis: a review

Follicular mucinosis (FM) is an epithelial reaction pattern characterized by follicular mucin accumulation. It has been described in association with various inflammatory and neoplastic cutaneous disorders. FM is generally divided into a primary benign idiopathic form and a secondary form usually occurring in association with cutaneous lymphomas (especially mycosis fungoides), among other entities. Distinction between the two forms can be challenging as they share many overlapping features and the lack of a single diagnostic tool to differentiate between the two. Making the distinction may require evaluating and correlating the clinical, histologic, immunohistochemical, and molecular studies together. Long-term clinical follow-up also remains very important. In this review, we describe the different entities associated with FM, its pathogenesis, and possible therapeutic options.

A Systematic Approach to the Cutaneous Lymphoid Infiltrates: A Clinical, Morphologic, and Immunophenotypic Evaluation

CONTEXT.—

The evaluation of cutaneous lymphoid infiltrates, both neoplastic and inflammatory, occurs very frequently in routine dermatopathologic examination and consultation practices. The "tough" cutaneous lymphoid infiltrate is feared by many pathologists; skin biopsies are relatively small, whereas diagnostic possibilities are relatively broad. It is true that cutaneous lymphomas can be difficult to diagnose and that in many circumstances multiple biopsies are required to establish a correct diagnostic interpretation. As a reminder, one should understand that low-grade cutaneous lymphomas are indolent disorders that usually linger for decades and that therapy does not result in disease cure. It is also important to remember that in most circumstances, those patients will die from another process that is completely unrelated to a diagnosis of skin lymphoma (even in the absence of specific therapy).

OBJECTIVE.—

To use a clinicopathologic, immunophenotypic, and molecular approach in the evaluation of common lymphocytic infiltrates.

DATA SOURCES.—

An in-depth analysis of updated literature in the field of cutaneous lymphomas was done, with particular emphasis on updated terminology from the most recent World Health Organization classification of skin and hematologic tumors.

CONCLUSIONS.—

A diagnosis of cutaneous lymphoid infiltrates can be adequately approached using a systematic scheme following the proposed ABCDE system. Overall, cutaneous T- and B-cell lymphomas are rare and "reactive" infiltrates are more common. Evaluation of lymphoid proliferations should start with a good sense of knowledge of the clinical presentation of the lesions, the clinical differential considerations, and a conscientious and appropriate use of immunohistochemistry and molecular tools.

Follicular mucinosis in patients with hematologic malignancies other than mycosis fungoides: A clinicopathologic study

BACKGROUND

Follicular mucinosis (FM), which is defined by mucin accumulation within follicular epithelium, may occur in mycosis fungoides (MF). FM without MF is occasionally reported in systemic hematologic malignancies and may be diagnostically challenging.

OBJECTIVE

To describe clinicopathologic characteristics of FM in patients with hematologic malignancies other than MF.

METHODS

Clinical data and histopathology features were analyzed in patients with FM and hematologic malignancies diagnosed between 1994 and 2017.

RESULTS

A total of 18 patients with FM and systemic hematologic malignancies without cutaneous T-cell lymphoma (CTCL) were identified; 9 of them were discovered after hematopoietic stem cell transplantation. No patients with non-CTCL-associated FM (n = 46 [37 biopsy specimens]) developed CTCL during a mean follow-up of 4.3 years. Of the cases of CTCL associated with FM (n = 44 [31 biopsy specimens]), MF was the most common subtype (n = 38), although other CTCLs were identified. FM in patients with non-CTCL hematologic malignancies differed clinically from those with MF-associated FM, presenting most frequently with erythematous papules (P < .0001), without plaques (P <.0001), without alopecia (P = .001), and without histopathologically identified epidermal exocytosis (P = .013).

LIMITATIONS

A retrospective study in a single cancer center.

CONCLUSIONS

FM can present in systemic hematologic malignancies, including after hematopoietic stem cell transplantation. Papular lesional morphologic and histopathologic features may help to distinguish these cases from MF.