Misnomers in Dermatology: An Update

Abstract

The name of a condition in dermatology, gives a clue regarding the clinical feature, etiology, or histopathology of the disease. A disease might have been termed wrongly due to its resemblance to another known condition. Misnomers often mislead a physician regarding the etiology or histopathology of the condition. Here is a list of misnomers, with explanation, and the appropriate name in parentheses.

Introduction

What was known?

Many of the following conditions are known to be misnomers, in spite of which the term is being used.

The term “Misnomer” suggests an interpretation that is known to be untrue. There are many terms in dermatology lexis, which might mislead a physician regarding the etiology or histopathology of the condition. Though most of them have a synonym which describes the condition aptly, the misnomers are still being used. Here is a list of misnomers, with explanation, and the appropriate name in parentheses.

Acanthosis nigricans

Acanthosis nigricans is velvety hyperpigmentation, seen commonly in the flexures and neck. Histological examination reveals hyperkeratosis and papillomatosis but only slight irregular thickening of stratum spinosum, despite the term acanthosis.[1] There is no increase in the number of melanocytes. The dark color is due to hyperkeratosis rather than increase in melanin.

Acne keloidalis nuchae (Folliculitis keloidalis nuchae, Folliculitis Nuchae Scleroticans)

Folliculitis keloidalis is a chronic, inflammatory process involving the hair follicles of the nape of the neck and leading to hypertrophic scarring, papules, and plaques. The lesions do not occur as a result of acne vulgaris and neither are they keloidal.[2]

Acne necrotica miliaris (Propionibacterium folliculitis)

Acne necrotica miliaris is essentially a folliculitis, the lesions typically distributed throughout the scalp. It is an inflammatory reaction to Propionibacterium acnes and in severe cases to Staphylococcus aureus.[3]

Acne rosacea (Rosacea)

The epidemiology, etiology, and pathology of rosacea are quite distinct from acne vulgaris. The pathogenesis of rosacea is multifactorial, but is clearly related in part to vascular hyper reactivity.[4] The condition was named acne rosacea in the past due to involvement of the face and presence of erythematous papules and pustules akin to acne vulgaris.

Acne urticata

It is a chronic severely pruritic eruption, characterized by the development of pale red elevated wheal-like papules, surmounted by a vesicle with turbid contents, frequently associated with polycythemia vera.[5] There is no association with sebaceous glands.

Actinomycetoma

Mycetoma is derived from the Greek word ‘mykes,’ which means fungus.[6] Actinomycetoma is a chronic, suppurative, granulomatous disease with discharging sinuses, similar to mycetoma. It is caused by aerobic species of bacteria actinomycetes and not by fungi as its name suggests.

Adenoma sebaceum (Facial angiofibroma)

Adenoma sebaceum are symmetrically distributed small, red angiofibromas of the face seen in tuberous sclerosis. In the past, they were mistakenly called adenoma sebaceum due to its distribution in the sebaceous area of the face.[7]

Alopecia mucinosa (Follicular mucinosis)

Alopecia mucinosa presents as hair loss in hair-bearing areas; however, lesions can also occur on glabrous skin. The skin lesions in the acute form are seen as erythematous papules and plaques with variable scaling and patulous follicles. The chronic form is widespread and of diverse morphology, with scaly patches, papules, plaques, and nodules.[8] Histopathology shows deposition of mucin in the hair follicles and sebaceous glands. Thus, the term follicular mucinosis is more appropriate.

Arachnidism (Araneism)

The clinical syndrome following the bite of spider is arachnidism. This should be referred to as Araneism, as spiders belong to the order Araneae.[9] The class arachnids include spiders, scorpions, ticks, mites, and other over 1,00,000 named species.

Athlete's foot (Tinea pedis)

The incidence of Tinea pedis was initially noted to be higher in the population that wore occlusive footwear like athletes. However, dermatophytic infection of the foot is not specific to athletes. The risk factors include frequent wear of tight-fitting shoes, walking barefoot in public areas where the infection can spread, such as swimming pools, communal baths and showers, and reduced immunity.

Auspitz phenomenon

The eponymously credited sign was not first discovered by Heinrich Auspitz (1835-1886). Both Devergie Jeune (1860) and Hebra (1845) observed this clinical sign earlier, as did Robert Willan (1808), Joseph Plenck (1776), and Daniel Turner (1736).[10]

Axillary freckling (Crowe's sign)

Freckles are pigmented macules seen in sun-exposed areas. Thus, the term freckling applied to pigmented macules in the axilla, which is a characteristic sign of neurofibromatosis, is not appropriate as axilla is a commonly photoprotected area.

Botryomycosis (Granular bacteriosis, bacterial pseudomycosis)

Botryomycosis is chronic granulomatous reaction to bacterial infection, in which bacteria like Staphylococcus, Pseudomonas, Escherichia coli, Proteus, and Streptococcus species form granules similar to those seen in mycetoma. It is not a fungal infection as the name indicates.

Candidal miliaria (Decubital candidiasis)

Lesions of candidial miliaria start as isolated vesico-pustules that contain the yeast, on back of bedridden patients. The term candidal miliaria is better avoided, as there is no clinical or microscopic evidence of miliaria.[11]

Capillaritis (Pigmented purpuric dermatosis)

Capillaritis comprises of chronic purpuric eruptions that commonly occur over the lower limbs. Histopathology shows lymphocytic perivascular infiltrate limited to the papillary dermis. Evidence of vascular damage may be present, and the reaction pattern may then be termed lymphocytic vasculopathy, vasculitis, or capillaritis. However, the extent of vascular injury is often insufficient to justify the term vasculitis.[12]

Cavernous hemangiomas (Venous vascular malformation)

Vascular malformations are localized defects of vascular morphogenesis always present at birth. They have a quiescent endothelium and do not exhibit the markers of proliferation seen in hemangiomas of infancy. As they are not proliferating lesions, the suffix ‘oma’ (meaning ‘tumor’) has been deemed inaccurate. Other similar misnomers are sinusoidal hemangioma and verrucous hemangioma.[13,14]

Chicken pox (Varicella)

Varicella is caused by varicella zoster virus and is characterized by vesicles on an erythematous base. The disease has no relation to chickens. Chicken pox comes from the Middle French term “chiche pois” for chickpea, a description of the size of the lesion.

Chronic superficial glossitis in syphilis

Chronic superficial glossitis is a feature of tertiary syphilis. The pathology is deep-seated and not limited to the surface of the tongue as the name suggests.[15]

Collagen disorders

Connective tissue disorders are also referred to as “collagen disorders”. Connective tissue also contains other elements, such as elastin and glycoproteins, along with collagen. The term “collagen disorders” should be restricted to inherited conditions that affect the synthesis or expression of collagen, such as Ehlers–Danlos syndrome and osteogenesis imperfecta.[16]

Dissecting cellulitis of scalp (Perifolliculitis capitis Abscedens et suffodiens)

Dissecting cellulitis of the scalp is a chronic suppurativa disease of unknown etiology. It is not a bacterial infection of the skin as the term cellulitis suggests. Follicular blockage is proposed to be the initial event that leads to retention of material and dilation of follicles. On subsequent rupture of the follicle, released keratin and organisms initiate a neutrophilic and granulomatous response.[17]

Dyshidrotic eczema (Pompholyx, vesicular eczema of palms and soles)

Pompholyx is referred to as dyshidrotic eczema due to the connection with sweat-gland activity, as the condition is worse in hot weather. This term should be abandoned, as no causal relationship with the sweat glands or sweating has been demonstrated.[18]

Dysplastic nevus (Nevus with architectural disorder, atypical mole)

Atypical moles are larger and have irregular, indistinct borders. Dysplasia means change in phenotype, i.e. size and shape of the cell. Atypical mole shows no significant dysplasia on histopathology but only architectural abnormality with poorly circumscribed nests of cells.[19]

Eccrine spiradenoma (Spiradenoma)

Lesions of spiradenoma usually manifest as solitary, one cm, gray, pink, purple, red, or blue nodules on the upper half of the ventral side of the body. The histogenesis of spiradenomas is not exclusively eccrine; many lesions also show apocrine differentiation.[20]

Erythema migrans chronicum (Erythema migrans)

About 90% patients develop erythema chronicum migrans at the site of tick bite. Even if untreated, the lesion fades, usually within a few weeks to months. It is not a chronic condition.[3]

Erythema toxicum neonatarum (Erythema neonatarum)

The term toxic means a physiological state produced by toxins or other poisonous substances. Erythema toxicum neonatarum is a common benign vesiculopustular neonatal eruption, which affects 50% full-term neonates. The condition resolves spontaneously over 1-2 days.

Fibroepithelioma of Pinkus

It is generally regarded as a rare variant of basal cell carcinoma (BCC). Therefore, fibroepithelioma is not an accurate term for this disease.[21]

Follicular atrophoderma

Follicular atrophoderma is characterized by follicular indentations occurring over the extensors of upper and lower limbs. On histopathology, no abnormalities of the elastic fibers have been found (nor any evidence of atrophy of the epidermis, hair, or dermis), making the term atrophoderma (atrophy of the skin) a misnomer. The hair follicles are abnormally wide, plugged, and surrounded by an inflammatory cell infiltrate.[22]

Gnaw warts

Gnaw warts are callosities resulting from the habit of biting or chewing the side or knuckle of the finger.[23]

Granuloma faciale

Granuloma faciale is characterized by single or multiple cutaneous nodules, usually occurring over the face. Occasionally, extra-facial involvement is also noted, most often on sun-exposed areas. Histopathology shows mixed inflammatory infiltrate with a predominance of neutrophils and eosinophils, mainly in the upper half of the dermis. No granulomas are found.[24]

Granuloma fissuratum (Acanthoma fissuratum)

Granuloma fissuratum is a reactive skin process resulting from chronic trauma, commonly from ill-fitting eyeglasses and is seen over the intertriginous area of contact between the ear lobe and the tempero-occipital area. There is acanthosis with attenuation of the rete centrally, and dermis shows variable chronic inflammatory infiltrate without any granulomas.[25]

Granuloma gluteale infantum

Erythematous to violaceous nodules and plaques appear in the napkin area of infants as a complication of diaper dermatitis, frequently at a time when the dermatitis is improving. They tend to occur on the convexities of the napkin area and are definitely not confined to the gluteal region. On histopathology, there is dense inflammatory infiltrate occupying the full depth of the dermis, comprising lymphocytes, plasma cells, neutrophils, eosinophils, and histiocytes. There are no granulomas.[26]

Herpes gestationis (Pemphigoid gestationis)

It is a rare autoimmune bullous dermatosis of pregnancy. The disease was originally named herpes gestationis on the basis of the morphological herpetiform feature of the blisters.

Hidradenitis suppurativa (Acne inversa)

The primary pathology in hidradenitis suppurativa is not suppurative inflammation of the apocrine sweat glands but an occlusion of the hair follicles, comparable to acne vulgaris. It is acne inversa because, in contrast to acne vulgaris, the disease involves intertriginous localizations.[27]

Horn cysts (Horn pseudo cysts)

A cyst is a closed sac without connections with adjacent tissue. The intra-epidermal whorls of invaginated keratin found in seborrheic keratoses are not true cysts, because each connects to the skin surface via a prominent ostium. Horn pseudocysts have been proposed as a more appropriate term.[16]

Hot-comb alopecia (Central centrifugal cicatricial alopecia, follicular degeneration syndrome)

It is a progressive vertex-centered alopecia, seen most commonly in women of African descent, who use hot combs to straighten hair. The etiology is a constant source of debate, as there are reports of the condition occurring without the use of hot combs.[28]

Impetigo herpetiformis (Pustular psoriasis of pregnancy)

Generalized pustular psoriasis, with symmetrical and grouped lesions, and often starting in the flexures seen in pregnancy is impetigo herpetiformis. It is not bacterial infection unlike impetigo, which is caused by Staphylococci or Streptococci.

Infantile myofibromatosis (Infantile myofibroma)

Infantile myofibromatosis presents as a solitary nodule 70-80% of the time, most commonly on the head, neck, and trunk. The most common form of this disorder is solitary, not multicentric as the name implies.[21]

Kaposi sarcoma

Kaposi sarcoma is a multisystem angioproliferative disorder characterized by proliferation of spindle-shaped cells, neo-angiogenesis, inflammation, and edema. There is controversy as to whether these proliferative cells truly represent a malignant neoplasia versus an inflammatory hyperplasia. Therefore, the term sarcoma used in the description of this condition may not be warranted.[21]

Keratoderma blennorrhagica

Keratoderma blennorrhagica is characterized by vesiculo-pustular waxy lesion with a yellow-brown color, seen commonly on the palms and soles in reactive arthritis. Blenorrhagia, which means excessive flow of mucus, is an old term for gonorrhea. However, reactive arthritis occurs commonly due to non-gonococcal urethritis. Thus keratoderma blennorrhagica is a traditional misnomer.[29]

Keratosis follicularis (Darier's disease)

Darier's disease is characterized by keratotic papules predominately affecting the seborrheic regions such as the upper trunk and the head and neck areas. Most papules in this condition are non-follicular in location.[30]

KID (Keratitis, ichthyosis, and deafness) syndrome (Keratodermatous ectodermal dysplasia/KED)

In a review of the literature, the most frequent cutaneous features of KID syndrome were erythrokeratoderma 89%, alopecia 79%, and reticulated hyperkeratosis of the palms and soles 41%. The KID acronym does not accurately define this entity since the disorder is not an ichthyosis, and not all patients have keratitis early in the course. Thus, it has been suggested that this syndrome should be included under the general heading of congenital ectodermal defects as a keratodermatous ectodermal dysplasia (KED).[31]

Knuckle pads

Garrod's pads

Knuckle pads are benign, well-circumscribed, skin-colored papules or plaques, located over the dorsal aspects of the metacarpophalangeal (MCP) and interphalangeal (IP) joints. In most reported cases, lesions occur over the proximal interphalangeal (PIP) joint, not over the knuckles.[32]

Lupus miliaris disseminatus faciei/LMDF (‘FIGURE’ facial idiopathic granulomas with regressive evolution)

The term LMDF, also known as acne agminate, resulted from a historical classification of this condition as a presentation of tuberculosis. It is now known that the condition is neither tuberculous in etiology nor related to acne and is a distinct entity.[33]

Lupus anticoagulant

Lupus anticoagulants (LA) were originally described in patients with systemic lupus erythematosus (SLE) and clinical bleeding. LA causes increased risk of both arterial and venous thrombo-embolic events. The riddle of the anticoagulant effect in vivo and the apparent procoagulant effect in vivo remains unsolved.[34]

Lupus pernio

Large bluish-red and dusky violaceous infiltrated nodules and plaques that occur on the nose, cheeks, ears, fingers, hands, and toes in sarcoidosis is lupus pernio. Perniosis describes localized inflammatory lesions on acral skin, which occurs as an abnormal reaction to cold in susceptible individuals. Thus, lupus pernio has no association either with tuberculosis or with cold exposure.[35]

Lymphangiosarcoma (Stewart-Treves syndrome, hemangiosarcoma)

Stewart-Treves syndrome is a rare, cutaneous angiosarcoma that develops in long-standing chronic lymphoedema. Lymphangiosarcoma seems to arise from blood vessels instead of lymphatic vessels. A more appropriate name is hemangiosarcoma.[36]

Lymphangioma circumscriptum

Superficial lymphatic malformation

Lymphangioma circumscriptum is lymphatic malformations, which can be located anywhere on skin surface giving a frog spawn appearance. These lesions are rarely circumscribed and often have deeper dermal and subcutaneous anomalies.[37]

Malignant pustule of anthrax

Malignant edema

Primary lesion of anthrax which begins as a papule and then becomes a vesicle is malignant pustule. The lesion is not purulent and pustules, if present, represent secondary infection due to streptococci or staphylococci.[16]

Melanoacanthoma

Melanoacanthoma is a histological variant of seborrheic keratosis. As most of these lesions resolve spontaneously in a few months, the term melanoacanthoma, implying that it is a tumor, is inappropriate.[38]

Microdermabrasion

Microdermabrasion treatments exert direct effects on the stratum corneum and epidermis. Only on aggressive treatment, the reticular dermis may be affected rarely.[39]

Mycosis fungoides (Cutaneous T Cell Lymphoma)

Mycosis fungoides is the most common variant of primary CTCL, generally associated with an indolent clinical course. The exact etiology of mycosis fungoides is not yet established. It is not caused by fungal organism.

Nasal glioma

Nasal glioma denotes a probable variant of encephalocele developing from neuroectodermal tissue invaginated through the nasofrontal fontanelle. A stalk of fibrous tissue may pass from the lesion into the foramen cecum. It does not originate in the nasal tissue.[40]

Necrobiotic granuloma (Palisading granuloma)

The term necrobiosis refers to change in collagen associated with an accumulation of histiocytes. Necrosis refers to collagen change and biosis to cellular proliferation. Necrosis can occur only in cells, not in collagen fibers. Hence, palisading granuloma is a more suitable term.[41]

Nevus depigmentosus (Achromic nevus)

Nevus depigmentosus is a congenital hypopigmented macule, which is not progressive. The areas of leukoderma are hypomelanotic and not amelanotic.[42]

Nodulocystic acne (Nodular acne/Grade IV acne)

Acne ‘cysts’ are not true cysts because they are not lined by an epithelium. It is, therefore, more accurate to describe such lesions as nodules.[43]

Ocular albinism

It is suggested that the term “ocular” albinism may be somewhat of a misnomer, and that cutaneous involvement is present.[44]

Palisaded encapsulated neuroma

Histopathology of PEN shows a bulbous expansion of a peripheral nerve, with Schwann cells forming uniform, broad, interlacing fascicles that are spaced in a clear or mucinous matrix. There is no palisading arrangement of cells.[45]

Pautrier's microabscess

Pautrier's microabscess is a collection of atypical lymphocytes found within the epidermis of lesions of cutaneous T-cell lymphoma. An abscess characteristically refers to a collection of neutrophils or alternatively to a cavity formed by liquefaction necrosis within a solid tissue.[16]

Peruvian wart/verruga Peruana (Oraya fever, Carrion's disease)

Oraya fever is caused by Bartonella bacilliformis. The eruption in the chronic phase of the disease is characterized by erythematous papules, which become pedunculated. Some lesions may become very large. They are not viral infection as suggested.

Piezogenic pedal papules

The term piezogenic means ‘producing pressure,” when in fact these lesions are produced by pressure. It is postulated that pressure induces herniation of fat through connective tissue in the dermis of the heels.[22]

Porokeratosis

The cornoid lamella corresponds to ostia of eccrine glands or hair-follicles occasionally, which led to the term “porokeratosis;” however, this finding is fortuitous, since the peripheral border of porokeratotic lesions is moving centrifugally and, therefore, it cannot be permanently bound to epidermal adnexae (that are definite structures). Moreover, the occurrence of lesions over mucous membranes further shows that porokeratotic lesions do not necessarily develop within epidermal adnexae.[46]

Preauricular sinus

Preauricular sinus is a common congenital anomaly, which appears as small dents, commonly on the ascending limb of helix of the external ear. The sinus opening is usually on the auricle and not preauricular.[47]

Pretibial myxedema

Thyroid dermopathy

Pretibial myxedema or thyroid dermopathy is an autoimmune manifestation of Graves’ disease.[48] The lesions first appear on the antero-lateral aspect of the lower limbs and only later extend to the back of the legs and feet. Thus, the term is a double misnomer, as the lesions are seen in hyperthyroidism and are not limited to pretibial area.

Pubic lice (Phthirus pubis/crab lice)

While the organism is typically found in the pubic area, it may affect any part of the body with secondary hair, including the eyelashes and eyebrows of children.[16]

Pyoderma gangrenosum

Bacterial infection of the skin is pyoderma. Pyoderma gangrenosum is a rare, non-infectious neutrophilic dermatosis.[49]

Pyogenic granuloma (Lobular capillary hemangioma)

Pyogenic granulomas are neither infectious nor granulomatous. The lesion usually occurs in children and young adults as a solitary glistening red papule or nodule that is prone to bleeding and ulceration.[50]

Ringworm (Tinea corporis)

Tinea corporis is commonly referred to as ringworm, which stems from the annular appearance of the lesions. No worms are associated with this condition.

Scleredema

In scleredema, the collagen bundles are thickened without being hyalinized and stain normally with eosin and the trichrome stain. There is neither sclerosis nor edema.[51]

Scleredema adultorum

Scleredema can be categorized into three clinical subgroups. Group 1 includes scleredema after acute respiratory infection (scleredema adultorum). Most of the patients in this group are of pediatric age.[52]

Sebaceous cyst (Epidermoid cyst)

Most epidermoid cysts are acquired and appear to be derived from the infundibular portion of a hair follicle. These cysts are not of sebaceous origin.[53]

Seborrheic keratoses/Seborrheic wart/Senile warts

Seborrheic keratosis is the most common benign tumor in the elderly. The lesions are well-defined and flat initially, later they develop a velvety to verrucous surface. Seborrheic keratosis is derived from keratinocytes and not sebaceous glands, and neither are they viral in etiology.

Sign of leser trelat

Two European surgeons, Edmund Leser (1828-1916) and Ulysse Trélat (1828-1890), are separately credited with providing the first description of this sign. However, they were apparently observing cherry angiomatosis in patients with cancer rather than seborrheic keratoses. Hollander first linked internal cancer with seborrheic keratoses in 1900.[54]

Soft wart (Acrochordons)

Skin tags are called soft warts, as they are soft on palpation.

Synovial sarcoma

Immunohistochemical and ultrastructural differences between normal synovial cells and the cells of synovial sarcoma indicate that the tumor is not derived from synovium, leading to suggestions of alternative terms including connective tissue carcinosarcoma and soft tissue carcinoma.[55]

Tinea amiantacea (Pityriasis amiantacea)

Pityriasis amiantacea represents a particular reaction pattern of the scalp to various inflammatory scalp diseases. There is shiny thick asbestos-like scale attached to the hair shaft and scalp in layers. The most frequent skin diseases associated are psoriasis and seborrheic dermatitis.[56] It is not associated typically with dermatophytic infection.

Tinea cruris

Tinea cruris is a common dermatophyte infection of the groin, genitalia, pubic area, and peri-anal skin. The designation is a misnomer because in Latin, “cruris” means of the leg.[57]

Tinea versicolor (Pityriasis versicolor)

It is superficial non-inflammatory infection of the skin caused by Malassezia species of fungi. It is not caused by dermatophytes.

Transient acantholytic dermatosis (Grover's disease)

Transient acantholytic dermatosis (Grover disease) is a self-limited disorder, characterized by pruritic, papular, or papulo-vesicular eruption, most commonly occurring on the trunk that resolves over weeks to months, but it can be persistent and may repeatedly recur for years. Thus, the term transient is not appropriate.[58]

Trichoadenoma

Trichoadenoma is a benign follicular neoplasm that consists mostly of small cystic spaces that exhibit infundibular and isthmic differentiation, enveloped by sclerotic stroma. Hair follicle does not show glandular differentiation.[59]

Trichomycosis axillaris (Trichobacteriosis)

Trichomycosis axillaris is a common tropical disease affecting the hair shafts in sweat gland-bearing areas like armpits and pubic region, characterized by nodular concretions along the hair shafts caused by Corynebacterium tenuis. It is not a fungal infection, which is limited to the axilla.[60]

Tuberculoid nerve abscess (Segmental necrotizing granulomatous neuritis)

In tuberculoid spectrum of Hansen's disease, cutaneous or peripheral nerve trunks may show multiple swellings with caseous necrotic material within them. The term “segmental necrotizing granulomatous neuritis (SNGN)” has been suggested for these lesions, a term that describes the pathology of the lesions accurately.[61]

Trumpeter's wart

By definition, wart is a hard rough lump growing on the skin, caused by infection with certain viruses. Trumpeter's wart is a hyperkeratotic nodule that develops on the upper lip of trumpet players due to friction.

Water wart (Molluscum contagiosum)

Molluscum contagiosum is also called water wart, as the lesion appears pink to translucent.

What is new?

Some of the lesser-known misnomers have been compiled in the above list. An explanation why the condition is a misnomer is given.