How , Where and When to Make a Biopsy ?

Considering the more than 2000 dermatoses it gets clear, that clinical morphology alone in many cases is not sufficient for making a correct diagnosis. Histomorphology can provide additional significant information in many but not in all cases. In order to save efforts, patient’s inconvenience and costs it is important to know not only how and where to make a biopsy but also when a dermatopathologic investigation is mandatory and helpful in order to avoid misdiagnoses and wasting patients distress, time and money. Without being comprehensive some typical examples for various possible constellations are described.


Introduction
C linical dermatology and dermatopathology are two sides of one coin.They mutually complement each other.In clinical dermatology one looks at the skin from outside, in dermatopathology one looks at the same thing from "inside".The microscope "translates" the clinical macromorphologic features into the corresponding histomorphologic terminology.In order to combine both to a meaningful diagnosis it is mandatory, that the clinician and the (dermato-) pathologist communicate and understand each other and discuss the clinico-pathologic correla ons 1,2 .Trea ng pa ents for a wrong diagnosis may not only harm the pa ent but also generate unnecessary costs.Therefore, taking a biopsy should be considered whenever the clinical diagnosis is not clear.The three basic ques ons in this context are: how, where and when to make a biopsy.

How to make a biopsy
The excisional biopsy is the op mal procedure, since it not only provides a sample of the full lesion including surrounding normal skin but also is a therapeu c interven on by removing the pathologic lesion.Limita on may be given by the size of the lesion.Small single tumours are most appropriate for an excisional biopsy.The sample ssue should not be larger than 10 to 20mm in order to guarantee proper fi xa on in an appropriate vessel, in which the sample is completely surrounded by buff ered formalin.
An incisional biopsy takes only part of the lesion, which is too big to be completely excised.Like in the excisional biopsy, a spindle shaped ssue sample is excised usually from the border with the scalpel, cu ng ver cally to the skin surface.
The shave biopsy removes only the superfi cial part of a lesion, including the epidermis and the upper part of the dermis, leaving the lower dermal parts and the subcu s.This is diagnos cally suffi cient, when the pathologic changes are in the upper skin levels, like for example in nodular prurigo.
The punch biopsy is easy to perform with disposable devices.Depending of the size of the punch, wound closure may be neglected.
When superfi cial material is suffi cient for microscopic inves ga on, smear or debris is sampled.Processing of debris material is more diffi cult than with a solid biopsy sample due to the small pieces fl oa ng in the fi xa on medium.

Where to make a biopsy?
Basically there are fi ve op ons to take a biopsy.
In tumorous lesions, which are too big for being totally excised with an excisional biopsy, the sample will be taken from the centre of the lesion either by spindle excision or by a punch biopsy.In order to provide op mal material for the processing of the ssue sample (fi xa on, cu ng, microscopic inves ga on) it is important that the ssue is not necro c.
Taking a (spindle) biopsy from the border of the lesion, including normal and diseased parts of the skin, is indicated in infl ammatory dermatoses, especially if the lesion shows central regressing like for example in superfi cial fungus infec on, psoriasis or in granuloma annulare.
In deep infl ammatory condi ons with involvement of the lower parts of the dermis and the subcutaneous fat ssue, like in erythema nodosum or panniculi s, a deep biopsy including the subcu s is indicated.When making a punch biopsy, the size of the punch should be as wide as possible.
Superfi cial shave biopsy is a subop mal procedure.The advantage is, that no wound closure is needed.Usually it is suffi cient in dermatoses, whose major pathologic changes are located in the epidermis and the upper dermis like in psoriasis, eczema, nodular prurigo, lichen planus.
Scarifi ca on and sampling debris is an appropriate procedure in for example leishmaniasis or lepromatous leprosy.The debris collected may be diffi cult to be kept together in the embedding procedure.Anatomical structures are certainly lost with this material.Contamina on with blood should be avoided.

When to make a biopsy?
The gold standard for making a diagnosis is the clinical evalua on, based on localisa on of the lesion(s) and their distribu on and the morphology of the single primary lesion.This also has been the basis for the classifi ca on of dermatoses since the work of Willan and Bateman 200 years ago 3 , which in general s ll is followed to day in most textbooks.In 70-80% of the most common dermatoses in rural areas 4,5 (eczemas, acne, pigment disorders, ur caria) proper diagnosis can be made by clinical evalua on without any addi onal diagnos c procedure.However the remaining 20-30% include rare diseases or dermatoses simula ng common dermatoses, which may lead to misdiagnosis and mistreatment.This may be harmful for the pa ent and generates loss of me and unnecessary costs.
In cases with doub ul clinical signs, a biopsy is mandatory, when the histologic features can be clearly diagnos c and provide a high diagnos c impact.Examples are toxic epidermal necrolysis (TEN) versus staphylococcal scaled skin syndrome (SSSS); scalp psoriasis versus seborrheic derma s of the scalp; plaque psoriasis of the trunk versus pityriasis rubra pilaris or patch/plaque type mycosis fungoides; acute eczema versus pemphigus foliacius; psoria c erythroderma versus sézary syndrome; ur caria or ur caria vasculi s versus acute febrile neutrophilic dermatosis (sweet syndrome); pityriasis rosea versus secondary syphilis; lupus erythematosus versus rosacea; lichen planus of the anogenital region versus lichen sclerosus et atrophicus; intertriginous eczema or psoriasis versus langerhans cell his ocytosis (his ocytosis X); paget's disease or perimammillar psoriasis versus eczema; melanoma versus junc onal nevus or angiokeratoma.There are many other dermatoses which clinically may look alike and can only be diff eren ated by appropriate histologic inves ga on.Special types of basal cell carcinomas tend to grow subclinically beyond visible borders.In these cases Microscopic controlled surgery (Mohs technique) 6 is indicated in order to remove all branches of the tumor, which in case of uncomplete excision give rise to recurrences.Especially in facial localisa on close to eyes, nose, ear or mouth repeated excisions may result in cosme c misconfi gura on.By complete 3-dimensional evalua on of the excised ssue sample(s) with appropriate labelling of the borders according to the Mohs technique, the tumorous lesion can be completely removed by minimal sacrifi ce of normal ssue.This technique is extremely helpful but very elaborate and me consuming and therefore should be restricted to very special cases with a high threat of recurrence due to incomplete excision.
Making a biopsy in dermatoses, which clinically present with a clear-cut diagnosis, is op onal and can be performed just for having addi onal confi rma on.It creates addi onal costs without providing appropriate benefi t, except when done for research purposes.
In some dermatoses, microscopic inves ga on can be even confusing, since the histologic features may lead to wrong diagnos c conclusions.In these cases the clinical features are pivotal for the diagnosis, since the histology may reveal similar or even iden cal pictures of diff erent diseases.Examples among infl ammatory dermatoses are transient acantholy c dermatosis (Grover's disease) which shows similar acantholy c split forma on as seen in pemphigus benignus familiaris (Hailey-Hailey).However the clinical presenta ons with small papules in Grover's disease and large plaques mainly in the large skin folds are completely diff erent.Chronic gra versus host (GVH)-reac on histologically simulates lichen planus; the history however certainly diff eren ates both condi ons.The histologic changes in diff use scleroderma are iden cal with those seen in localised scleroderma (Morphea), whereas the clinical features are diff erent.It may be impossible to diff eren ate histologically the changes seen in dermatomyosi s from acute systemic lupus erythematosus.The clinical symptoms elucidate the correct diagnosis.With reference to tumorous condi ons, the histologic diff eren a on of keratoacanthoma (KA) from well diff eren ated squamous cell carcinoma (SCC) is based on history, which is in the range of weeks in KA and months in SCC: Anaplas c large cell lymphoma, CD 30 posi ve and lymphomatoid papulosis show similar histologic but diff erent clinical fatures and courses.
There are also situa ons, in which neither the clinical nor the histologic presenta on are suffi cient for making a correct diagnosis.For example pseudolymphomatous infi ltrate and cutaneous follicle center cell lymphoma clinically and histologically look perfectly alike and it is the course -spontaneous regression or con nuously progressive-which fi nally will reveal the correct diagnosis.
Many other diseases can create diagnos c problems.The list is far from being comprehensive, but some more dermatoses shall be men oned: ur caria versus ur caria-vasculi s, parapsoriasis versus ini al mycosis fungoides or nonspecifi c eczema, spindle cell tumors of various histogene c especially mesenchymal origin, nevus Spitz versus spitzoid melanoma and many others.
Nevertheless looking not only for the clinical feature but also at the histology is the clue in many diagnos c dilemmas and can avoid mistreatment, which is harmful not only for the pa ent but also for the public healthcare budget.
The Nepalese Society for Dermatopathology has been founded 3 years ago under the patronage of the DISHARC-clinic in Kathmandu.Now there is an increasing number of Dermatopathologists in Nepal, who are trained in both, clinical dermatology and dermatopathology.They are prepared for assis ng with their exper se in providing appropriate consulta ons for be er healthcare for pa ents with ambiguous dermatologic diagnoses.